Depending on synth used you may be able to find the conversion software online even if they do happen to be in Roland format.
I'd worry more about the floppies themselves being readable.

What synth? How old are the floppies? What format?

Some will load with a simple file extension renaming like OP said. In my experience that is more likely than saving as SMF on Roland stuff. Saving as a MID file more likely. Some may need something like SAMdisk. Hard to say with so few clues, but the fact it's on floppies seems notable to me.

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