The 8.0.150x or 9.0.150x versions were like an interim version number the .1500 initially was used whilst compatibility was checked. If it passed compatibility then the update should have completed and you ended up with version 9.0.2006.

This might just be because you still have avast 8.0 on these systems, is this correct ?
If so I would suggest doing a manual update on one of them and see how that goes before trying it on the others.

Personally I wouldn’t put the Program Updates on Automatic (leave it on Ask) as if there is something intensive/important running in the background, etc. I don’t think you would want a program update going on.