Variety we all might have, but nobody can be sure.

Just found out that Czech 50 Haleru 1993 has an undistinguishable variant with slightly different alloy: Aluminium 97% - Magnesium 3% instead of normal "Aluminium 99% - Magnesium 1%".

56,000 pieces material trials were made. Point is that they were all released into circulation.

Normally, they can be recognized by the fact that they were more shiny than usual. But after 15 years of circulation, we can only guess. Maybe some chemist could find out?

Who asked for a chemist?

Seriously we would need some X-ray analyzers to not destroy the coin.

If there are other chemicals involved in the alloys an EDS (energy dispersion spectroscopy) can do the trick. An EDS doesn't tell you percentages very well, but it tells you chemicals present, so if there are variations that include other chemicals this can help in determining which variation it is. The only thing is that we need a full list of trials and what elements were involved. Is anyone here really that involved in numismatics to go try to figure this out?

More important would be to find out concerned machines.

The main issue with your coin Jarcek is the coins were added to common circulation and the coin is already withdrawn, so there is a high risk these coins have become really scarce.

Oh no, they are still very common... Many were left behing for children plays and for poker gamers

Problem is that they are first year issue, and they are all worn.

Are this Gablonz or Hamburg coins?
In 1993 70 million of these were minted in Hamburg and 30 million in Gablonz.

I can't really be bothered with varieties, Unless there's a design change or a major change in metal (i.e going from sterling to 50% silver or changing from silver to cu-ni) then I'm just going to collect one of each coin.

According to the file, seems to be Jablonec.

Yes; 56 000 from Jablonec.