Depends on the Brifter. When I got Boreas built up I went for 105 brifters as at that time Ultegra was not available as suitable for a triple. The 105 brifters would do either. I may at some later date have wanted to go for a triple and did not want the expense of buying new brifters.

However when I did change from compact to Triple- I had to buy a new front dérailleur. The double did not have enough throw for a triple. Whether a triple FD would work on a double I do not know.