This is in continuation of Pumpkins and Pumpkins 2.

Six pumpkins - each having a different weight - are weighed two at a time in all 15 sets of two. The weights are recorded as: 27, 36, 39, 45, 48, 51, 54, 57, 63, 66, 72, 75 and 81 pounds.

• Precisely two of the values occurred exactly twice, but these values were only written down once.
• Each of the individual weights (in pounds) is a positive integer.

Derive the weights of the pumpkins and which two values occur twice.