this is hard to explain but i will try 
I arranged my 24-word seed phrase in 4 lines of 6 words
I put the seed phrase in the metamask (it allows up to 24 words) and when I get to word number 12 I realize that I can log in with that seed phrase (I clarify that I had one of 24)
how can this be possibleā¦ someone explain to me?
check if I had funds and nothing xd
do NOT put your Trezor seed into MM, you are compromising it.
Use MM as it is intended, pair it with Trezor as per manual: Apps:MetaMask - Trezor Wiki
And MM recognizes the seed because also 12 word seed is possible, but it is not correct one.
Every combination of 12 words has a 1 in 8 chance of being a valid seed. This means that the first 12 words of your 24-word seed have a 1 in 8 chance, also your last 12 words, also any middle 12 words.
Note that itās a seed, not your seed. You can spend all day generating empty 12-word seed wallets.