96: Custom mark already declared

In metadata declarations a name beginning with an ampersand & refers to a custom mark. The custom mark is expected to consist of a single small or capital letter, a–z or A–Z, or a single digit 0–9 right after the ampersand. It must be unique. However, in your file the same custom mark is declared at least twice.

Solution

Make sure to declare each custom mark only once. Its name is case-sensitive, so you can declare both &a and &A though.