The El Vez said: "Orchestra Left, row T seats 9 and 11 (they are not separated, the numbering is just weird...."
Not at all weird.
Many theatres have three blocks of seats on the main floor. The center section are numbered consecutively in the 100s. 101, 102, 103, 104, etc.
The section on the left has seats in consecutive odd numbers: 1, 3, 5, 7, and so on.
The section on the right is consecutive even numbers: 2, 4, 6, 8, and so on.
Seat 101 in a center section will almost always share the aisle opposite seat 1 in the Left Section.
The seat numbering may appear confusing at first, but it helps decrease any confusion with duplicate seat numbers.
An easy way to remember what sections are where is a simplistic political formula. When standing in the back of the house, odds are on the far left, while evens are the far right.