I think I must miss something in the process, maybe it will be obvious to you so here is a video :
https://myspace.com/frenchhardcoresucks/video/dividing-midi-messages-using-copperlan/109402895
@ Danoise : I did not see your latest answer, but anyway you can see in the video link that it’s set up exactly like you mentionned, or maybe I missed something, but I can’t see what 
I just spent more than half an hour trying again to get it working, but without succes 
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I tried to turn the problem in all sorts of way, but there seems to be no solution. I wondered if that wasn’t a soundcard problem so I tried on another but no result. and the problem must be in Copperlan because I tried to connect VMidi to other softwares and that did not work either so the trouble is from the duplication of the signal. But everything is set like Danoise advised me, and anyway you can’t do much more various connections…
I’m getting mad to know that it’s almost there, and that other people here managed to make it work, and that’s not my case.
Please if you have any idea 
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Well, the only thing i could do was recording my own attempt with two instances of Renoise 2.8.1 You can see the errormessage about vmidi2 already being used and then i change it to vmidi1 and both instances receive the signal.
What i see in your video however is that you also assign vmidi1 to clock in and clock out and that doesn’t work, if you assign two clock signals to the same midi device, copperlan shuts down one of them. (I noticed Copperlan giving this hint) perhaps that is your problem.
So set both clock out and clock in to “none”, close Renoise to save the preferences and see if you can get it working from there.
Below i have attached my video, you have to click it and then the still image to see the original size gif animation.
Thanks
I scrutinized your video to see if there is anything that would help me understanding within the configuration where the problem is.
What you underlined about clock I already tried it out and it did not work neither : on Renoise I set the clocks to none like you and it did not work, and on Copperlan I tried to break the linked clocks and it did not work neither.
I still cant get the solution out of that… Finally maybe Renoise won’t help me playing live sessions… Too bad because it seems there is a solution but I can’t get how to proceed with it
I doubt that, Renoise just opens up the vMidi ports and waits for answers, nothing more, your Renoise sessions don’t seem to get any messages at all which is quite an indication somewhere in Copperlan things go hayware or before. There are more people that can use this solution so it may perhaps either be a problem with your midi device sending signals that should not be send or there may perhaps be a hidden option in Copperlan that allows to interpret certain midi messages differently to translate them correctly.
I noticed in the latest update a change in the 0-velocity note message was being translated differently than was received in a former edition.
Perhaps the guys from Copperlan could give you some advises or other users on the Akai forums can learn you some tricks, perhaps the MPK can be toggled into a specific mode, or compatible mode when turning it on.
I have no idea what the MPK does, else i would have figured this out to the bottom myself.
Thanks a lot for the time you spent around here and the help provided till there.
I just sent a message to Copperlan, I don’t know if I will get feedback, but if I finally find a solution I’ll post it there to help eventually other users in the same case…
Now I’m gonna probably go around the akai forums to see if it’s some help…
So here is the answer from Akai. I’m not surprised and I can understand this is the best answer they can give, but I haven’t got news from Copperlan team yet :
“Its hard to tell because you are using a software that I am unfamiliar with, and a third party MIDI utility that can cause more trouble than anything if no used correctly. I can answer any question you have regarding how the hardware works and why it does what it does, but you may need to reach out to the app developers to understand their limitations.”
Hum, perhaps time to try a different approach?
I have previously used MIDI-OX along with MIDI Yoke to pull of these kinds of tricks. MIDI Yoke is a virtual MIDI cable driver, and MIDI-OX a general purpose MIDI utility.
But then, I’m still using Windows XP and those programs haven’t been updated since 2007… 
If you feel adventurous, download them both from here: http://www.midiox.com/
Once installed, it really should be as simple as starting the MIDIOX utility and then go to Options -> MIDI Devices
Then select the input device (MPK) and one or more of the MIDI Yoke ports. The program should then establish routing between the devices.
Thanks for the link but it seems I can’t install it on my PC (Windows 7), it crashes all the time before installing is finished…
I’ma look for something else on the same type of software on the net…
Yea, once I upgrade this machine I would be in the same situation. Windows XP is now what, 12 years old?
Anyway, many such tools exist. LoopBE1 is a good alternative for newer OS’es, and perhaps this, along with a little tool like “Midi Trix” to create the actual routing could help you?
I will give it a try…
But I think I maybe have found kind of a different solution…
I said to myself “what’s the problem in the end in what you want to do live with Renoise and your MPK ? Launching patterns with the pad is what is creating problems in the end because you don’t have enough possibilities with it… What other way could you use to launch patterns ? Mouse clicking ? No way, it’s not that practical in a live session… What about the pc keyboard itself ?”
From there I searched a tool that would convert the PC keyboard into a midi controller assignable on Renoise via Midi mapping. I found “Virtual Midi Controller LE”, which allows a little more than 10 octaves (120 notes, so 120 patterns in my example) that can be assigned to trigger midi controls in Renoise. And while I’ve got this one running and mapped, I still have my MPK Mini fully responding, so I can play melodies, tweak knobs or even use the 2 banks of pad without interference.
I still have to test on a huge Renoise file including one hour of patterns and all the VSTI’s & effects I need into my songs, because this will maybe too much for my CPU, but this way I just need one instance of Renoise. And in case The VSTIs make it too big for CPU, I think I remember there is a function that save CPU from VSTis by exporting them into “Instruments” on Renoise, isn’t it ?
Well I’ll try this way and tell you if this suits my needs…
Forget about my “solution”… There was something I still needed to test and it revealed it’s not valuable : Assigning as an example C4 on the Virtual Midi Controller to launch one pattern, then it will also be launched by my MPK when I will press the C4 note > it seems that the C4 from VMC LE and the C4 from my mpk is considered by Renoise as the same message… />
I watched a video from one of the creators of copperlan on you tube, where he first assigns “controller settings” using a learn function. I did not do that before so maybe here is the problem, BUT, proceeding exactly the same way as he does on the video, nothing happens when I tweak the knobs or play notes on my MPK… Did you guys proceeded such “controller learn” to make it work with Copperlan ?
@Danoise : I had seen LoopBe1, but it seems more dedicated to create routing between DAWs or PC than to duplicate midi messages from one controller, but maybe I did not understand everything very well, that world is quite obscure to me as I already said previously… 
Nopes i don’t need to and you shouldn’t need to if your controller uses plain note values.
Have you tried splitting your controllers by midi channel? (putting your Akai on channel 2 and your virtual midi keyboard use it on channel one) This is usually the way to distinguish the same note in a different way and Renoise supports it for triggering patterns (it wil mention something like “cha 2 note C-4”).I think if you have done that, your solution will work.