When new incoming call comes to tr2.xxxxxxx.ru, new session is being created and accounting begins. Further, call forwarding to another server, to fs2.xxxxxxx.ru, and new session is being created again.

2015-07-23 11:22:42.514095 [NOTICE] switch_channel.c:1054 New Channel sofia/external/73472460000@tr2.xxxxxxx.ru:5080 [26777290306690-93831426613199@192.168.217.156]
...
2015-07-23 11:22:42.574084 [INFO] mod_xml_radius.c:1123 mod_xml_radius:  Accounting Start success
2015-07-23 11:22:42.574084 [DEBUG] switch_core_state_machine.c:164 sofia/external/73472460000@tr2.xxxxxxx.ru:5080 Standard ROUTING
2015-07-23 11:22:42.574084 [INFO] mod_dialplan_xml.c:558 Processing 73472460000 <73472460000>->79373057071 in context public
Dialplan: sofia/external/73472460000@tr2.xxxxxxx.ru:5080 parsing [public->originate_leg] continue=true
Dialplan: sofia/external/73472460000@tr2.xxxxxxx.ru:5080 Absolute Condition [originate_leg]
Dialplan: sofia/external/73472460000@tr2.xxxxxxx.ru:5080 Action export(nolocal:h323-call-origin=originate) 
Dialplan: sofia/external/73472460000@tr2.xxxxxxx.ru:5080 parsing [public->public_mult] continue=false
Dialplan: sofia/external/73472460000@tr2.xxxxxxx.ru:5080 Regex (PASS) [public_mult] destination_number(79373057071) =~ /^(79373057071)$/ break=on-false
Dialplan: sofia/external/73472460000@tr2.xxxxxxx.ru:5080 Action set(hangup_after_bridge=true) 
Dialplan: sofia/external/73472460000@tr2.xxxxxxx.ru:5080 Action bridge(sofia/internal/79373057071@fs2.xxxxxxx.ru:5070) 
2015-07-23 11:22:42.574084 [DEBUG] switch_core_state_machine.c:214 (sofia/external/73472460000@tr2.xxxxxxx.ru:5080) State Change CS_ROUTING -> CS_EXECUTE
...
2015-07-23 11:22:42.574084 [NOTICE] switch_channel.c:1054 New Channel sofia/internal/79373057071@fs2.xxxxxxx.ru:5070 [e059ad7f-b2f8-4beb-b1f3-249bc431cfc4]
...
2015-07-23 11:22:42.634059 [INFO] mod_xml_radius.c:1123 mod_xml_radius:  Accounting Start success

Thus, one call is being counted twice (for incoming to tr2, and then for outgoing from tr2 to fs2). But we need to make mod_xml_radius counts this call only once, how can we handle it?
Thanks
--

Arthur