First off individual housing for both specimens. That will solve many many potential issues right there & eliminate lots of risks as well.
They should only be housed together for breeding purposes & if housed together should NEVER be fed together in the same tank EVER.
Check ALL other husbandry aspects & make sure the regurge wasn;t due to being too hot or too cold. Know the EXACT temps no guessing. Looking at around 75F for coolside temps & 80-85F for warm side temps. An extreme either way can cause regurges.
Prey that is heated too hot or too cold can cause regurges as well as having too large of a meal most likely the case here. Why one would increase so much at once is beyond me, mind you so is group housing

You do NOT want to feed the one that regurged for at least 7-10 days & then feed it a meal SMALLER than what it would usually take so it can build up its digestive juices again over time. Feeding it too much or too soon or both will result in another regurge or a series of regurges if continued to be fed after doing so.
Best bet right away is to get individual setups for ALL snakes & ensure that all husbandry needs are properly being met.
Also provide lots of fresh water as regurges severely dehydrate young snakes & can be fatal. Mark
P.S. basic husbandry 101
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Mark's GONE SNAKEE! working with select Colubrids (Corns, GB Kings, EIs) and Woma Pythons
All stock parasite free and established on F/T prey. No PMs please email at
gonesnakee@shaw.ca