Guten Tag!

The last time I shot my M1 (prone unsupported) I experienced a double fire two times - yup, I can see why full auto Garand/M14 wasn't a good idea
I rule out the ammo/soft primers as I used Danish military surplus and my suspicion goes to the hammer and sear.
Also had unvoluntary bump firing in mind, but after thorough inspections, it seems that the hammer is barely caught by the sear. Unfortunately I don't have any pictures of parts in good shape for reference.
The trigger assembly passes the safety test though (https://www.garandgear.com/m1-garand-inspection/)

Is this excessive wear? Already ordered some spare parts.

https://ibb.co/7YbPCc
https://ibb.co/LvwSdL

Not milking the trigger were you?

Your trigger/sear and hammer don't look too bad IMO.

I had a rifle doubling, changing the trigger did not help. Learning to quit milking it solved the problem.

I had a club rifle with a likely home trigger job. When testing it, half the clip fired for every trigger pull. Trigger and hammer fixed it.

This, first determine if you are holding the trigger near the sear break point when firing.   The M1 and the M14 need you to keep pulling the trigger rearward so the trigger is not reset right at the break point.  The gun rebounds post firing off your elastic shoulder and can cause you to trip the trigger accidentally for the second shot.  

If you are sure it’s not that it’s time to buy a set of replacement parts.   ebay used to have a lot of new old stock parts in Italy.   I bought new in wrap bolts and hammers in years past from Italy.

I had the same issue. Changed the trigger, didn’t fix it, consciously avoided milking, didn’t fix it. Changed the hammer, that fixed it. Runs right as rain now.

Had this problem with a Winchester Service Grade. Erratic sear engagement. Removed the trigger group and disassembled it.
The trigger and sear looked fine. Hardly any wear at all. The hammer hooks were...worn. Swapped it with an NOS replacement
hammer and the problem went away.

I repaired a Garand that would double or even empty the clip once.

It was grime in the bolt/firing pin groove. Might want to check that.