Don't know. Suspect that they are offering different policy products that happen to be underwritten by the same Insurer. Is one policy is classic car Insurance without any no claims discount and the other a standard policy with no claims ?

The problem is that if you are still driving around with a policy that does not have a no claims discount, is the next time you come to arrange a policy elsewhere, it might present some hassle. i.e when arranging a normal policy again and asked for no claims proof, you will need evidence of the last policy with a no claims discount and then a letter from the other Insurers that you haven't had any claims with them. Now try explaining that to most companies out there and some might be difficult, as normally the no claims discount proof is from just last Insurance company.

Go back to the whoever has provided the quotes and discuss this with them.