What distance separates two gamma ray bursts that are 13 billion light years from Earth each but in opposite d?

Recently, a gamma burst was detected in the sky from a star about 13 billion light years away. Would it be possible for a detection of a gamma burst from a star 13 billion light years away in the exact opposite direction with respect to our galaxy? If yes, how far would the two stars be away from each other? I don't think it could be 26 billion light years?