Paul, the CHP El Cajon office's area of operation is covered by two different simulcast cells on the RCS (East and South). Because of the way the system was configured 10 years ago when CHP joined the system (before the East simulcast was built), their talk groups were split into two sets (East and South).
37888 is South Dispatch. 38880 is East Dispatch. CHP normally keeps them patched.
Hope this helps.