Lucases

There are 3 Lucases in Year 2 in Lucas's school. 2 Lucases in Lucas's class, inclusive of himself. The teachers and friends have to call their full name i.e. Lucas + last name.
We were rather surprised of how popular or common the name is. Dominic and I were saying we should have spelled his name as LUKAS.

Then Lucas told me
Lucas: Mom, do you know what my friends call me in school?
Me: Lucas Lim
Lucas: No. They call me Luk.
Me: Luke is the short name for Lucas anyway.
Lucas: Not Luke, but Luk. L-U-K.

I think this Luk will stay with him as these 3 Lucases will always be in the same year until the finish school.