You shouldn't need a triple since most compact cranksets are doubles. However, triples usually have cages long enough to clear the chain when on smaller rings than the 39t traditional road inner.
There's also a difference in the curvature and set angle of the cage, which better match the curverture of smaller outer rings, but this isn't critical.
What may be more critical, is the height of a braze on derailleur. While a clamp on standard derailleur can always be lowered, a brazed on derailleur may be limited and one made for compact may (or may not) sit lower. Since you can't move the braze on, this might be the clincher in making you decision.
IMO- start with what you have now, and check options only if it doesn't work out for you.
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