General GMAT Questions and Strategies | Retake GMAT 660?

I recently took the GMAT and scored a 660. The program that I want to get into has an average of 680. I called the school and half are telling me to re-take the test while the other half are telling me I should still be fine as I'm only 20 points away. I'm not sure who to listen to. This is my second GMAT that I got the 660 in. My practice tests did not reflect my score. I scored lower on the practice tests and did good on the actual test. So I'm confused if I should take it again or no.

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