Assuming you're a Catholic.
Can. 1248 §1. A person who assists at [i.e. attends] a Mass celebrated anywhere in a Catholic rite either on the feast day itself or in the evening of the preceding day satisfies the obligation of participating in the Mass.
From: http://www.vatican.va/archive/ENG1104/_P4N.HTM
Can. 917 A person who has already received the Most Holy Eucharist can receive it a second time on the same day only within the eucharistic celebration in which the person participates, without prejudice to the prescript of ⇒ can. 921, §2.
From: http://www.vatican.va/archive/ENG1104/_P39.HTM
>>711126
I didn't find any justification based on the length of a "canonical Sunday". It would be a strange thing to think about, anyway. If the canonical Sunday began at Saturday evening, shouldn't the canonical Monday begin at Sunday evening? In which case, the Sunday evening mass wouldn't fulfill the Sunday obligation.