Is there a way to duplicate column headings in Flextable without adding a .1,.2, etc.?

Question

I am reporting the findings of linear models which compare several vegetation factors to different species of frogs in the study system. It would be best if I could report the findings with the vegetative factors as rows, then have the columns as the coefficient, p.value, significance, etc, and have a heading over each group of columns with the frog species. However, to do this, column names have to repeat. I am using flextable and the col_keys function does not allow me to repeat names of columns. Do you have any advice for if what I'm hoping for is possible?

Here is my current code:

coqlmflex <- add_footer_lines(coqlmflex, "* < 0.01, ** < 0.05, *** < 0.01")
coqlmflex