The first code you see is the IPV4. Or the traditional IP
11.11.11.11
The second part you see is the IPV6. Or the new IP format
2001:0db8:85a3:0000:0000:8a2e:0370:7334
In the above case -
[B]2001:0db8:85a3[/B] These first three groups can be part of the network identifier, specifying the network segment the address belongs to.
0000:0000 These groups are often used for subnetting within the network, allowing for internal organization and routing.
8a2e:0370:7334 The last three groups are typically used as the interface identifier, uniquely identifying the interface of the device on the network.
So it's absolutely not uncommon for the first part of the IPV6 on the same network to be same.
What you need to be concerned about is the interface identifiers or the last part.
There are methods that allow systems to allocation an IPV6 - some of these are based on your device's Mac Address (EUI-64), others use
Privacy Extensions to generate random modifiers and finally some rely on allocation by DHCP (DHCPv6).
So ideally, a different interface identifier should show you as two different devices for most websites trying to track you.