You've learned Italian with your method and are moving on to French. On one hand it seems all "the same" words should be connected to "the same" memory, but on the other hand, it could be complicated, especially if you add mnemonic helpers. If you use the same mnemonics for genders, etc. with the new language, it could make it challenging.
Once you're learning language #2 via this method, you'll want to do whatever you can to make the two languages different from each other. I'd suggest looking for unique memories when possible. It will help keep the two languages separate, and the same goes for the mnemonics and any pictures you use.