It's a reworked DWM LP08 from 1915, and Ingolstatdt worked on it twice.
The E/ZaJt is a a very early depot acceptance and probably dates to the early 1930s. The other acceptance (HZaJt3) is a second rework and dates to the middle of WW2, probably around 1941-1944.
For some reason, Ingolstatdt reworked Lugers are very often reworked twice like this one. Not sure why.