Is this normal?

Hi, I am new to the forum and to growing tomatoes. I live in North Norfolk, UK. I have planted half a dozen Garden Pearl tomato seeds. All have germinated however, one seedling has 4 cotyledon leaves as opposed to two. Apart from the number of cotyledon leaves, the seedling looks identical to the others. Is this normal or should I discard the seedling as a mutation?

I have read some information about 3 leaf cotyledon seedlings but this is very limited and I have found nothing on 4 leaf varieties. Unfortunately I have been unable to access the FAQs so have not been able to check these.

Any help appreciated.
Thanks