Yes, the pan law is applied on each send, and this is not a bug but by design. This has been discussed many time before.
This is why the default setting is 0 dB pan law. It is "the setting that causes the least number of questions about pan law" (Schwa,
http://forum.cockos.com/showthread.php?t=41345)
So if you just set the default to 0 dB, and change pan law only for the tracks that you need it for, things work fine.