The reason is probably because 2.6 saves names in replays differently than in 2.5
If opened in notepad, a replay setup in 2.5 looks like
"#!/usr/bin/toribash
#made with toribash-2.5
VERSION 8
FIGHT 0; bleh2 [Guru]Mosier uke
AUTHOR 0; [Guru]Mosier
NEWGAME 0;500 10 0 0 0 2 175 1 0 classic 0 0 100 0 0"
Whereas a replay in 2.6 looks like
"#!/usr/bin/toribash
#made with toribash-2.6-beta2
VERSION 8
FIGHTNAME 0; bleh
BOUT 0; [Guru]Mosier
BOUT 1; uke
AUTHOR 0; [Guru]Mosier
NEWGAME 0;500 10 0 0 0 2 100 0 0 classic 0 0 100 0 0 2 1 0 2"
Notice how 2.6, instead, the player names are shown seperately with bout # next to them...
It probably shows tori and uke since the replay saved in 2.6 and opened in 2.5 since 2.5 doesnt recognize the new formatting style, so it just defaults to tori and uke