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IANAL, but check out this law.stackexchange thread. It pertains to the BSD license, but it's very similar

And the 2nd answer seems to say that no, you can't just recopyright something. https://law.stackexchange.com/a/4150

Some answers seem to disagree. I, as a non-lawyer, think as long as the git commits make it clear who authored what, it's a non-issue.

See the Software Freedom Law Center's guide:

There are multiple examples of how to recopyright MIT-style source under the GPL.