Only probes from the first DTrace object file will be included
From the original Joyent bug report:
When trying to link together multiple object files generated by DTrace only the probes from the file listed first will be included in the resulting binary.
Attached is a simple project, in it if you link a.dtrace.o before b.dtrace.o aprobe will be included, and vice versa bprobe will be included.
One would expect both probes to be included.
I found this while trying to work around the fact that you can't have usdt probes in both an application and in a static library that application links against. (Only the application probes will persist)