I don't understand why someone would want to be baptised twice, unless they see their first baptism as unsound. I know there are people who don't recongise infant baptism and are baptised by full immersion as an adult. Why would someone want to be re baptised because they have changed sex? They still have the same soul and are the same person.
www.bbc.co.uk/news/uk-england-manchester-35441852
Surely there is one baptism for the remission of sins. The gender of that person is irrelevant. Baptism is not a naming ceremony, but a sacrement of the church. It's formally joining the church and surely you can only do that once. A transgender person can be baptised like anyone else, if they have not been baptised before.
I am in favour of a service of blessing for a transgender person, but theologically you can't be baptised twice.