They don't need any such arrangements.
DropCatch owns like 50% of all registrars (don't recall exact numbers but in this zone). SnapNames also owns many and with NameJet added (these two are both owned by web.com), 75% of the internet is firing at once to capture so everyone else is just left watching.
Their model is simple: They bought everyone else as much as they could so now they have thousands of registry connections firing at once. Everyone else has like one or a few max. DC owns more than 1500 registrars (edit= approximate). It's almost impossible to compete with these guys.
It's sheer market domination - and you can't do anything about it while the rules stay like that.
If we get to speculation, I'd rather worry about something else. Why do they require you to place backorders (starting at $10 for discount club) 15 minutes in advance of the drop window? This doesn't make sense. 15 minutes is enough for someone to overbid you if they have access to the data.
I have no direct proof of this, again it is just speculation, but I can tell you that frontrunning is still rampant in the domaining world, with many registrars still doing this shady stuff today. So this made me wonder and it is one reason why I don't use DropCatch with backorders, other than, perhaps, bidding in an existing auction.
Edit: this is an old article from 2016 about DC buying even more registrars back then:
http://domainincite.com/21309-dropcatch-spends-millions-to-buy-five-hundred-more-registrars