Yup, that's the... beauty of analogue parts.
The 6581 revision selection is currently broken and fixed to R4 3789 (very late production). To be corrected in the next release.
Some SIDs from HVSC #55 aren't played, eg:
Shoot, HVSC changed the file PSID file version for 2SID stereo tunes. I wasn't aware of that. To be corrected too.