When i render tunes with 2.8, the first sounds are double hit. so i get KICK,KICK, when there is only 1 KICK 
it seems that the playroutine is triggered 2 times…
what plugins are you running, does it also happen when rendering with only native dsp and/or no effects?
Post is still a bit vague… first sounds? How many? One? Post the song that you have a problem with, or maybe a cut down version. If you solo the kick track (or remove everything else) is it still misbehaving?
… are you trying to render a song with the custom delay feedback chain trick?
Renoise has two Interpolation modes. “Cubic” and “Arguru’s Sinc.” Does the problem happen in both modes?
“[Arguru’s Sinc] results into the best possible sample playback quality, but may also lead into some unwanted effects.”
See Sinc Interpolation for more info.
if there is a kickdrum to start with, it does this kick 2 times.
it only double hits if i use any vst
for example rendering only a sample track, it dont do it