Now i think about it, it is maybe the wiki which is wrong about it, i can't find from where the info that up to 4 sounds can be streamed simultaneously comes from.
No, i forgot to mention. This bug affects only stream. However this is observed even with two instances of the sound played at the same time. I'll attach to the bug tests RP & DP.
Can confirm in 1.19.4, Note that it creates a ghost item
Can confirm in 1.21.8.