to force an open door

[birdeen's call]

Is there such an idiom in English? It exists in Polish and I think in German too. I don't see any matches in the British National Corpus, but a Polish dictionary says it's how we should translate the Polish idiom. Did they simply carelessly translate the idiom literally or is there something to it?

[birdeen's call]

But I think "to force a door open" means simply "to open a locked door by force", doesn't it?
The Polish idiom means "to try to solve an already solved or non-existent problem". I'm sorry I didn't provide the meaning in the question.

[birdeen's call]

Thanks!!

[Tdol]

Or carry coals to Newcastle??

Though this one may be a bit too British for international purposes.