More than 2,000 test ballots were counted as though they were ballots cast by voters during Cambridge’s election last week, an error officials blamed on the vendor overseeing the city’s election system.

As a result, the unofficial tallies posted on the night of the election included thousands of extra votes — more than 1,300 in the race for seats on the School Committee, more than 600 in the race for City Council and more than 150 for a ballot question. When officials recalculated the votes, the makeup of the School Committee was changed.

The unofficial results released in the hours after polls closed showed Eugenia Schraa Huh had defeated incumbent David J. Weinstein for the fifth and final seat on the School Committee. But with the test ballots removed, the results showed that Weinst

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