i STUDY EVERY DETAIL AND WHAT I HAVE SEEN IS THAT SOMETIME DURING THE WAR THE UPPER INSIDE HAVE BEEN HANDPAINTED.
It was not for so the helmet would look good often was this for seeing that this is “my helmet”
No damages just used during some years. It had double decals that always leave something if they have been there for sometime. First it was an order to scratch away one decal because it was a target for snipers etc. some took away both. If they where in SS it always went away if they want to stay alive as POW.
The number 64 (size) for 57 is on the side but I have not seen anything more than a shadow of the rear stamp inside the helmet.