Collecting bunter errors? (9x19 czech)

I assume that as with coin collecting where there is interest in mint errors on coins, that there must also be some occurrence of bunter errors on cartridge headstamps which are known to collectors? Given that quality control would notice after a certain time I also presume that there would not be too many making it out into the retail or contract stream, making it hard to verify since one would need two or more cartridges to verify the error as a consistent bunter error?

I recently realized that I had a new double of a headstamp which I already had (found in a lot of mixed Czech 9mm in an Interarms repack box having mixed headstamps). This led me to check my own example to see which was better quality, and I realized that I actually already had two of the same in my collection box, one with GMCS bullet, and one with CNCS bullet. On the one with a CNCS bullet I did however notice a lump of extra or unstamped metal near the top of the “0” in 50, which also appeared on the newly found double that I had which had a GMCS bullet.

I found this interesting since I assume that when instances of same headstamp like this have two different projectiles loaded, that this must take place at a certain point during production when projectile type is changed, and not just randomly intermixed? Or would they have been intermixed? Maybe it was just too small of an error to notice, but in any case I find it interesting and there must be other examples out there. Anyone who collects these might want to check the below photo and see if theirs also has the error: