When crossing over occurs between two linked genes in an f1 dihybrid testcross, the frequency of the parental phenotypes will always the frequency of the recombinant phenotypes, compared to unlinked genes.

Greater.

Explanation:

Linked genes may be defined as the genes that are present on the same chromosome or may close enough that can pass in the next generation together.  

The results of the crossing over in linked genes result in the formation of recombinant progeny. The frequency of the recombinant progeny will always be lesser than the parental progeny and cannot be more than 50%. If it is more than 50% these genes are considered as linked genes.

Thus, the answer is greater.