Both can be run simultaneously, they're separate installs.

I have run both on the same Windows 10 machine BUT MMW4 pointed to the original copy of my music (D:\Music) and MMW5 to a copy of this library of music (E:\Music).

This was because - during the testing of various early versions of MMW5 - I wanted to "cross-check" if anything was going on.

Whilst there have been some issues in the past, I think the last 2 or 3 versions of MMW5 have addressed these.

We now have CD burning with MMW5, auto-organise and auto-tag work well and addition of lyrics with MMW5 has improved.

As a consequence of these improvements, I now run only MMW5 on my Windows 11 machine and keep MMW4 on my old Windows 10 machine.

I recommend you try this BUT take some time to perhaps keep a back-up of your music AND the MMW4 database and MMW5 database.

Is there any problem with having MM5 and MM4 installed at the same time using the same music? I ask as for example MM5 doesn't have the "Extract fields" script available which I find very useful when fixing multi-artist albums. Thanks,

P.