Anyone from TRS able to answer please?
If by stacking you mean having similiar perk as bronze/silver/gold (say Rocket Man/Rocket Lord/Rocket King) they do stack.
Here you go:
Beat me to it
Worth noting Health Regen seem to have a cap at 60/s, but it might be a bug considering it seem to be the only perk having one.https://talk.turtlerockstudios.com/t/please-make-it-so-we-cant-select-the-same-perk/91083/14?u=mrtalha&source_topic_id=91546