Hello Shakil
In an MPLS L3 VPN, the VPN label is not the same for PE1 and PE2. Each PE router generates its own VPN labels for the VPN routes it advertises to its peers. However, when these labels traverse the MPLS network, they remain the same throughout the journey of the packet. When the packet arrives at PE2, you will see that it will have the same VPNv4 label.
This can be seen in the lesson, if you take a look at the output from the show mpls forwarding-table command on PE2, you will see the local label marked as 19, which is the same value as the VPNv4 label that was originally sent from PE1.
The VPN label used to reference a particular customer network remains the same throughout the communication. For example, in the 6VPE lesson, he PE2 router will assign a VPN label of 19 to the 2001:DB8:5:5::5/128 network (its own customer network) and will advertise that throughout the topology. PE1 learnes about that, and this is why in the output of the show bgp ipv6 unicast command, you can see a label value of 19.
When PE1 advertises its VPN label for its customer network of 2001:DB8:1:1::1/128, it too assigns the label number of 19, but this is independent of that assigned by PE2 to its customer network. The fact that the numbers are the same may be what is confusing. This is independent and can be any number. But these don’t cause any problems if they are the same because they are used in completely different contexts. Does that make sense?
I hope this has been helpful!
Laz