I was given the following question:

The cdc25 gene of the fission yeast Saccharomyces pombe encodes a phosphatase which dephosphorylates the tyrosine 15 residue of the cyclin-dependent kinase (Cdk). Dephosphorylation of tyrosine-15 of Cdk activates its kinase activity.
You introduced a 2nd copy of the cdc25 gene under control of the Gal promoter. The Gal promoter is active when yeast cells are grown on media containing galactose and repressed in cells grown on media containing glucose. How will the presence of glucose or galactose affect the cell cycle progression in this strain of yeast?

I understand how cdc25 works to dephosphorylate tyrosine-15 which then causes MPF to be active. I understand how a gene would behave under the control of a Gal promoter. I don’t understand what the introduction of a 2nd copy would cause. Can someone please explain this.

Thanks!