[c-nsp] Multicast issue

[R S]

My source multicast supplier is sending two flows for the same mcast group (224.0.4.4)

355715: Jun 11 08:55:45.870 CET: %SEC-6-IPACCESSLOGP: list 198 permitted udp 1.1.1.1(0) -> 224.0.4.4(0), 150 packets  
355717: Jun 11 08:56:45.871 CET: %SEC-6-IPACCESSLOGP: list 198 permitted udp 2.2.2.2(0) -> 224.0.4.4(0), 5827 packets  

in my C3925 (connected to the mcast supplier on g0/1.10) mroute table I see just one source active:

#sh ip mroute 224.0.4.4 count 
Use "show ip mfib count" to get better response time for a large number of mroutes.

IP Multicast Statistics
9 routes using 4458 bytes of memory
5 groups, 0.80 average sources per group
Forwarding Counts: Pkt Count/Pkts per second/Avg Pkt Size/Kilobits per second
Other counts: Total/RPF failed/Other drops(OIF-null, rate-limit etc)

Group: 224.0.4.4, Source count: 1, Packets forwarded: 4251, Packets received: 264466
  RP-tree: Forwarding: 0/0/0/0, Other: 260215/260215/0
  Source: 1.1.1.1/32, Forwarding: 4251/0/44/0, Other: 4251/0/0

If I do "clear ip mroute 224.0.4.4" the second source is added in mroute table:

#sh ip mroute 224.0.4.4 count 

IP Multicast Statistics
10 routes using 4984 bytes of memory
5 groups, 1.00 average sources per group
Forwarding Counts: Pkt Count/Pkts per second/Avg Pkt Size/Kilobits per second
Other counts: Total/RPF failed/Other drops(OIF-null, rate-limit etc)

Group: 224.0.4.4, Source count: 2, Packets forwarded: 2402, Packets received: 2424
  RP-tree: Forwarding: 0/0/0/0, Other: 22/22/0
  Source: 1.1.1.1/32, Forwarding: 48/0/44/0, Other: 48/0/0
  Source: 2.2..2.2/32, Forwarding: 2354/0/371/0, Other: 2354/0/0

Both has ingress and egress intf:

#sh ip mroute 224.0.4.4       
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
       L - Local, P - Pruned, R - RP-bit set, F - Register flag,
       T - SPT-bit set, J - Join SPT, M - MSDP created entry, E - Extranet,
       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
       U - URD, I - Received Source Specific Host Report, 
       Z - Multicast Tunnel, z - MDT-data group sender, 
       Y - Joined MDT-data group, y - Sending to MDT-data group, 
       V - RD & Vector, v - Vector
Outgoing interface flags: H - Hardware switched, A - Assert winner
 Timers: Uptime/Expires
 Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 224.0.4.4), 00:02:10/stopped, RP 172.21.15.2, flags: SPF
  Incoming interface: GigabitEthernet0/0, RPF nbr 10.11.254.33
  Outgoing interface list: Null

(1.1.1.1, 224.0.4.4), 00:01:26/00:02:03, flags: FT
  Incoming interface: GigabitEthernet0/1.10, RPF nbr 10.2.0.233
  Outgoing interface list:
    GigabitEthernet0/0, Forward/Sparse-Dense, 00:01:26/00:03:02

(2.2.2.2, 224.0.4.4), 00:02:10/00:03:23, flags: FT
  Incoming interface: GigabitEthernet0/1.10, RPF nbr 10.2.0.233
  Outgoing interface list:
    GigabitEthernet0/0, Forward/Sparse-Dense, 00:02:08/00:03:19

This works since the mcast flow is running, once it's stopped by supplier and restarted again in the morning I've to do again the "clear ip mroute xxx"

Any idea why I'm experiencing this behaviour ?

Tks