The meaning of this operation is that all or some components of one GDB (source) are added into another GDB (target) and the source is not changed. However, in such merging different conflicts may arise if there are components with the same names in the two merged GDB. These conflicts should be solved in the dialog of the user with the system.
All the issues connected with GDB merging are described in detail in chapter 59 “Merging GDB”