I think you mean 'Is Allison spelt with a double l or a single l?'
Both Allison and Alison are commonly seen.
rover
Allison is spelled with a double l or double l?
I think you mean 'Is Allison spelt with a double l or a single l?'
Both Allison and Alison are commonly seen.
rover
What I mean is, do we say "with a double l" or " with double l"?
Two ells, not two ayes.
I agree - I'd say "with two ells" not "with a double ell." However, others might find it more natural to say "a double ell." If you use the latter, use the "a."
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.
I actually have a friend called Allison and when she is giving her name she always says "Allison - double ell".
Remember - correct capitalisation, punctuation and spacing make posts much easier to read.
So I could just use it without the indefinite article?