What is seed?
Recovery seed is the ultimate backup of your wallet. All your private keys that are necessary for accessing your balances on public addresses and signing transactions are derived from the seed, it represents your wallet.
Seed is completely independent of the physical device (Trezor token) and vice versa.
You can have more devices with the same seed active on them. You can recover seed to any compatible 3rd party wallet.
More information: Learn about: recovery seed
How to verify seed?
You can check your seed by running so called dry-run recovery. BY running this process you can check that your seed words that are recorded offline were recorded correctly in correct order and also that this is the seed that is now active on your wallet (i.e. these words are backup of your currently active wallet. More info: Dry run recovery