I think that 'alright' is more colloquial than 'allright'. But I suppose they mean the same. Let me check at Longman dictionary... lol...
alright: Another spelling of ALL RIGHT that many people think is incorrect.
So it's ok it seems! It doesn't say 'allright' in the dictionary but 'all right'.
Hehehe, sorry if I got carried away but I'm going to study to become an English-Spanish translator and I like this stuff... 😉