From a Divisional supply section, 1941:
“Clothing of the Wounded”
“It has often happened, in order to quickly help people wounded and hurt in accidents, that their clothing items are cut off. By doing this, the wounded person is no longer sufficiently clothed after the bandages are applied. In the wounded collection points and field hospitals, it is not possible to issue new clothing to the wounded. In cases where cutting the clothing is necessary, this should be done whenever possible by separating at the seams, so that the clothing pieces can be sewn back together again.
“In some cases soiled and blood soaked wool blankets and Zeltbahnen have been destroyed. This is, due to the strained situation with raw materials, completely unacceptable. Soiled and damaged wool blankets and Zeltbahnen, that cannot be sufficiently cleaned by the units themselves, are to be returned to the Division supply office for cleaning and/or repair. Unit leaders are responsible for carrying out these measures.”
Please note this is 1941. Later in the war the situation became even more critical.
There is a persistent reenactor myth that soldiers could have acquired extra gear, perhaps from soldiers who had been killed. It didn’t work that way.
Generally speaking, they couldn’t cut up Zeltbahnen to make other things from them, or for fabric for repairs. They couldn’t take uniform and equipment items from the dead, to use or repurpose them. These items were Reich property and strictly controlled.