What kind of trait is expressed when two different genes from the same trait are present?

It depends on the gene in question, and the type of dominance of the trait.

For monogenetic traits (those controlled by a single gene), the dominant trait(s) will be expressed when two different alleles are present.

For example, if B leads to black fur and b leads to white fur:

Complete dominance would result in a rabbit with Bb having black fur.

Incomplete dominance - Bb would result in grey fur

Codominance - Bb would result in black and white patches/spots/etc.