When working with combined page numbers, such as 1-2, place the 1-2 within the style <RefPageNumber>. Insert the code lec following the 1-2. After the lec code, place the 2. This will ensure that the correct page number has the continuation letter as the lec code tells Duxbury which number to use as the continuation reference page number.
The same result can be achieved entirely with codes: use the code lea to set your reference page and lec to set the correct page number to have the continuation letter.