Combat damage is dealt at the same time (beginning of damage step), so there will 1 instance of 6 damage directed at one of the dinos. The other dino will modify that to 1 damage.
June 21, 2018 8:37 a.m.
Redirection effects don't change the source of the damage. It is true that all combat damage is dealt simultaniously, but much like if Temple Altisaur were double blocked there are 2 sources dealing damage to it and each source is reduced to 1 for a total of 2.
June 22, 2018 9:30 a.m.
So, who is right? Can either of you back up your answer with actual rules?
June 22, 2018 12:37 p.m.
Here is a reduced version of Rule 614.9, showing only the relevant information:
Some effects replace damage dealt to one creature, planeswalker, or player with the same damage dealt to another creature, planeswalker, or player; such effects are called redirection effects.
The operative term here is "same damage." As Gidgetimer said, the source of the damage remains the same--merely who receives it changes.