It would’ve been a cool visual, but thematically for the moment I’m glad it didn’t happen. Like, had we seen both it would’ve pointed out to us that he’s not really there. I loved the subtlety of the blue saber, hair/clothes, and lack of footprints rather than anything too obvious or noticeable.
But the two sabers don’t tell us is a projection of Luke. We kinda expecting Luke to use the green saber to fight Kylo (after all, the blue one was just destroyed). What is weird is to see Luke NOT using the saber. So is true that a lot of fan edits replaced the Anakin’s saber with the Luke’s one in the scene. But I really like the idea of Luke using the blue because it get Kylo furious and also because he is back to the old days, carrying on the father’s legacy and finally accepting to use the saber he refused by the beggining of the movie.
But also, if that is a projection and everyone is expecting to see Luke with the green saber, I really don’t understand why he couldn’t fight with both sabers, what would also make a nice paralell with Anakin fighting Dooku at the end of AOTC.