Coding advice please - non-repeatability

I need to ensure that if this action group is REapplied to a track, it applies its transform of TITLE, ARTIST, ALBUM, GENRE only once.

Currently my best solution is as you see there. For each field, if a copy is not already saved, I save a copy. Then I do the transform on the saved copy.

This is to avoid need for a condition on every step of the transform.

Can anyone see a better method?

That's it. If you want to take the actual values of fields like TITLE, ALBUM and ARTIST, combine them and add arbitrary strings, then the only way to be able to run the action group twice without totally wrecking everything, is to save the original values.