Well, it's not because a rule is named the same as another rule that you can't be affected by both. Two overlapping Covering Fire Templates generate two damage rolls, for example. You can have 2 or more models with Shield Guard covering the same model. 2 or more Extollers eligible to get the same soul with Gatekeeper (although only one would get it). A unit can be affected by 2 or more models with the Commander advantage. I could threaten to go on
This is different from identical rules that don't
stack, like Paralytic Aura, which means the bonus is +2 instead of +4.
In the case of 2 Lockers, I'd put that in the first category. I don't know what it would mean to 'stack' an effect that pulls you left with an effect that pulls you right.