Not going to fix things in Matinee as it will be deprecated
Placing a series of Play Sound Anim Notifies in an Animation and looping or playing that animation via Matinee multiple times causes the sounds to play all at once at the initial trigger of the animation in the Matinee Track.
Also Reproduced in Main Promotable-CL-2623997 & Releases 4.9.0-2625531
Edit MattK: It looks like this is breaking on the anim notify side but if you think it is matinee send it back.
Quick Reproduction, open attached Project, PIE
RESULTS: The first played animation correctly plays three seperate sounds, every successive animation and loop plays all three sounds on initial trigger.
EXPECTED: Sounds should only play at triggered frames in Anim Notify
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-18975 in the post.