Hi Rene,
Thanks for replying me…yes after set the router id in R3 now everything is up and not getting identifier error:smiley:
R3#sh running-config | include bgp
router bgp 2
bgp router-id 1.1.1.1
bgp log-neighbor-changes
R3#sh ip bgp summary
BGP router identifier 1.1.1.1, local AS number 2
BGP table version is 1, main routing table version 1
2 network entries using 288 bytes of memory
2 path entries using 160 bytes of memory
2/0 BGP path/bestpath attribute entries using 272 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 720 total bytes of memory
BGP activity 6/4 prefixes, 8/6 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
192.168.13.1 4 1 6 2 1 0 0 00:00:05 0
192.168.23.2 4 2 5 2 1 0 0 00:00:03 2
R3#sh ip inter brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 192.168.23.3 YES NVRAM up up
FastEthernet0/1 unassigned YES NVRAM administratively down down
FastEthernet1/0 192.168.13.3 YES NVRAM up up
FastEthernet1/1 unassigned YES NVRAM administratively down down
Loopback0 2.2.2.2 YES manual up up
Loopback1 22.22.22.22 YES NVRAM up up
R2#sh ip bgp summary
BGP router identifier 22.22.22.22, local AS number 2
BGP table version is 3, main routing table version 3
2 network entries using 288 bytes of memory
3 path entries using 240 bytes of memory
2/1 BGP path/bestpath attribute entries using 272 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 800 total bytes of memory
BGP activity 2/0 prefixes, 3/0 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
192.168.12.1 4 1 5 5 3 0 0 00:01:18 0
192.168.23.3 4 2 5 5 3 0 0 00:01:12 1
R2#sh ip inter brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 192.168.12.2 YES NVRAM up up
FastEthernet0/1 unassigned YES NVRAM administratively down down
FastEthernet1/0 192.168.23.2 YES NVRAM up up
FastEthernet1/1 unassigned YES NVRAM administratively down down
Loopback0 2.2.2.2 YES NVRAM up up
Loopback1 22.22.22.22 YES NVRAM up up
R2#sh running-config | include bgp
router bgp 2
bgp log-neighbor-changes
Then conclusion is if we want to use same loop back address in both router then 1st we should set the BGP router id(Like ospf) for specific identification, should not go for normal Router ID election process am i right Rene?
and one thing Rene in your topology picture 'How to configure BGP Weight Attribute" between R2(FastEthernet1/0) & R3(FastEthernet0/0) you didn’t add any IP address in topology picture 
but in lesson you add when you configured so if you don’t mind here i want to give you a suggestion please add then it will good for the topology picture.
Thanks & Regards,
Arindom