Their definitions seems to be the same, and both are said to be formal. Is there any difference between them?
unmatched: having no equal; better than any other of the same type
unparalleled: having no equal; better or greater than any other
When you're describing something that has no equal or is beyond comparison in conversational English, unmatched and unparalleled mean the same thing and can be interchanged.
However, the two words don't always have this meaning. As others pointed out, you might use unmatched to describe socks that don't make a pair, and in geometry, parallel means something very specific.
So, for all intents and purposes, the answer to your question is Yes, unless that's not the intended meaning of the word.