The first "as" is not part of the phrase, rather it should go with the phrase that comes before. "Just as fair" means equally fair. In today's English, fair means just, but in the past, it had additional meanings, like pretty, nice, bright, attractive. I hope this helps. In the future, you'll get better answers if you provide some context. Welcome to italki!

Could you give a little more context? With just what you've written, I'd say that the phrase "as just as fair" is something you found in literature. 'Just' is giving a person what is due to him; 'Fair' is giving equally to two or more individuals. "As just as fair," then is saying that the action was equally just and fair.

If you are talking about the poem "the road not taken", this means something like...choosing between two roads, or futures, that were different but potentially equally good.