Comment 4 for bug 437926

> Maybe this report should be turned into a feature request to optionally allow reusing the id of gradients
> when pasting objects? AFAIK this has been disabled to prevent unwanted fill&stroke changes when
> pasting objects from other documents that might use the the same id for a different gradient definition.

That's basically right. What actually used to happen was that the duplicate gradient got pasted with a new ID, but the object(s) that used the gradient remained pointing to the old ID, so you ended up with a shared gradient (even if the pasted gradient was supposed to be different) plus an unused gradient.

I think the best way to deal with the build-up of duplicate gradients that sometimes occurs is to add an option to Vacuum Defs (which should probably be renamed to something like Clean Up Document) that would find duplicates and make all objects use the same one. This has already been suggested in bug 170214.