To set multiple breakpoints in nonmember functions with overloaded names (same name, different type or number of arguments), use the stop infunction command.
To set a when breakpoint, use when infunction.
For example, if a C++ program has defined two versions of a function named sort(), one which passes an int type argument, the other a float, then, to place a breakpoint in both functions:
(dbx) when infunction sort {cmd;}