How to prevent endless proxy looping

Hi. I have a endless proxy looping problem. 1. problem username format: userid@my-realm@other-realm 2. on the freeradius, i proxy (nostrip) suffix @other-realm to partner's radiator radius server 3. on my partner then proxy back (nostrip) the same username base on @my-realm to my freeradius 4. so this username userid@my-realm@other-realm is bouncing in between my radius and my partner's radius endlessly 5. both my & partner cannot change the way we proxy, because it will impact on other proxy. Is there has any parameter which i can configure to terminate such proxy traffic? Thank you