I am 30 years old and single. I applied for a double TR visa last friday at the embassy in Sweden. Documents I presented to them was: airtickets and a pasport photo. Today when I got home I saw that they have given me a multiple entries non-immigrant visa instead. The free was paid in advance (2000 baht). I have checked their webpage and they claim that:

"Only applicable for retired person from 55 yrs+ or those who are married with Thai." I am neither of that. So is it possible that I will get problem with immigration when I get of the plane?

I suspect visa was put in wrong passport by the Embassy as believe 2,000 baht would be too law a price. If the visa is the computer printout stick on type with your passport information it should be accepted - but if passport info is wrong you need to get it changed.

Yep, agree with Lop.

If the visa has passport number and name on it, check that the details are you, if they are then you've got a lucky break If it's not you send it back to the consulate explaining the problem, they should fix it free of charge.

If the visa doesn't contain any personal data, no problem use it and enjoy.