I am not sure why but although if I have 2 of them in hand they appear as triggerable effects, only one can get summoned at once from a board wipe (like Black Rose Dragon) - even when 2 of my monsters have died at once.
Trigger effects that can Special Summon from hand work that way. (More or less just because Konami says so, not for any logical reason, but this is consistent with how they work in the TCG/OCG as well.) Note they don't actually even have to be Summoning themselves from the hand, it applies to stuff like Dragon Ice that can Summon from either the hand or GY, even if it's in the GY.
The dumb thing is that it only applies to effects that can Special Summon from the hand. You can activate, say, 3 copies of Dark Verger in response to a single Normal Summon just fine.
I think the issue is that only 1 card can be chained to the destruction of your monster at the same time, because if you activated it twice, the second interplanetary would chain to the special summon of the first one, which wouldn't make sense because its effect doesn't trigger at the activation of its first one. (was I clear?)
That's only true for things that respond to activations. For stuff that responds to other things, like attacks, Summons or a card being drawn, the entire chain is in response to that action, not the first link. For example, if the opponent Normal Summons Copy Plant, they can activate 3 copies of Dark Verger in their Grave at the same time, and you can then chain House of Adhesive Tape.
I suppose a more directly-comparable example would be that you can activate multiple copies of a card like Destiny Signal when a monster is destroyed by battle.
OrcishFarmer
OrcishFarmer