Meaning of et al. when referring to multiple papers with the same first author I am citing some papers with the same first author but different co-authors. 
For example, [1] is a paper by X, Y and Z, and [2] is a paper by X, A and B. Would X et al. [1,2] be appropriate here? because essentially et al. in [1] refers to people other than those referred to by et al. in [2]. 

There is a similar question about Harvard references. But I am interested in cases where only the reference number is shown in text. 

Update in my field in computer science, it's common to refer to the first author and use et al. When there are multiple ones. Usually the first author is regarded as the one who did the majority of the work.
I understand this "X and others" to mean one specific set of (unnamed) people, unless they are the same bunch I'd write them separately. Just like when I was citing two papers by Chen together, but they were different Chens.
Perhaps use "X, Y et al. [203] and X, Z et al. [205]"?