Not exactly an expert on this, but there is a huge volume of published work on math

coming out each month, and its not always easy to say whats original or not.

A typical remark for rejecting work, "oh that was done long ago in say geometrical algebra"

For plagiarism you would have to know before publication what others intend to

publish. Afterwards the correct is merely cite what is done, if you know about it.

So I think authentic plagiarism is rare. Plus todays mathematicians only work within

very specialized niches, usually what their advisor lead them to do. A Laglands style to try to unify is rarer,

but perhaps most needed. Plus math is often regarded as an indefinite, not exactly a science,

but more an art area. Say for a set of postulates, there are several starting and different sets for the same purpose,

Also if it is a consistant set , it is incomplete (Gödel)

Truly important results probably propagate very fast, like gunpowder,

becomes shared knowledge, properly belonging to no one.

There is known famous mathematician refusing prize over some doubdfull

behaviour in the community.

Some universities and officials have special protocols for themselves that keeps researches from plagiarism..

So this related for them..