No. It probably got crossed with a RL plant.

Mutation is another possibility.

The Cowlick's Brandywine seeds I germinated from the same package gave seedlings of both regular and potato leaves which is strange, but I'll just grow the potato leaf only because that's more typical brandywine in my book.

If you don't have fruit on the plants yet to confirm on-type fruit, I'd also def. consider the possibility of stray seed/seed mixups.

Stray seed or cross-pollination are far more likely than "mutation" which is quite rare. They revert rather than actually mutate.

But there is also the possibility, depending on the age of these seedlings, that what appear to be reg leaf now will develop into PL as the plants grow more. Very young PL are often mistaken for RL.

Dave

Which Brandywine are you referring to? Red Brandywines are regular leaf.