Validate 2Col syntax!
Brachylog (2), 4 bytes

ṇl₂ᵐ


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Full program (because this is a decision-problem; Brachylog full programs output false. if there was an assertion failure, true. without one).

Explanation

ṇl₂ᵐ
ṇ     Split input into lines
   ᵐ  For each line:
 l₂     Assert that that line has length 2


Subscripts on l are one of Brachylog's newest features (although still older than the challenge), and this is a good challenge to use them on.