Cousins with the same name...

So I have had a boy and girl name picked out for years for our second. My SIL got pregnant 4 months before me and just had her son in April. They named their baby Jackson (originally supposed to be Zeick) That is our baby boys name (spelled Jaxon). I am due in August but we have our hearts set on Jaxon and don't want to change it. My mom thinks it's weird but We are not changing his name because she stole our name! It's my husbands sister and he is even mad about this. Is that bad? We live an hour apart and hardly see them. I feel like we are being childish but we are set in the name we picked. Has anyone has this happen?