What are these things on a coin's surface?

Hi!

I have a coin which has some kind of “drops” on its surface. They are very flat, barely visible, unless the coin is tilted in an certain angle. To me these look like extra “drops” of metal, like something that was flowing on the coin then solidified. Both sides of the coin are affected.

Is this some known error? I have never seen this before. Any help is appreciated! Thank you.

Maybe a die clash?

Thank you, I think you are right. I have checked more carefully the coin surface and I can find traces of elements from the other face, so it looks lie a die clash.

Thanks again!