Can't be ruled out. Vomiting and diarrhea are symptoms and could be mistaken for food poisoning.

 

Also possible that whatever they procured at a pharmacy was not what it was thought to be and instead was something lethal, though I find it hard to imagine what a Camb pharmacy might be selling in way of tablets for food poisoning that could be lethal (drug allergy pretty unlikely given that 2 people were affecetd). . I have known cases where people were inadvertently killed by pharmaceuticals bought here as a result of sellers confusing product names (easy to happen given the range of imports from multiple countries) but these all involved drugs given by injection.

 

I can think of any number of scenarios that could explain one of them dying but both dying seems very, very odd. Even doing drugs you don't usually see two people simulataneously overdose unless there was something very wrong with the drugs obtained.

 

It is likely going to require fairly sophisticated/ comprehensive toxicological screens in addition to physical examination of the bodies  to identify cause of death.

Talk in the town is they took the wrong powder