Hi,
The East-Germans were mainly interested in producing reliable useable pistols, so they tended to give the pistols a good overhaul. Many small parts were changed out, parts numbers changed or X-ed out, new parts fitted, etc...
Some pistols were in good condition to start with and didn't have much parts replaced. Other pistols, having been in service during 2 wars and some 40 years, had more work done.
Many barrels were replaced, an indication is the lack of the original serial number and a lone crown/N proof on the bottom of the barrel.
This page from a DDR 1960's gun manual shows the VoPo version in all it's glory. Note the grips:
