They will only pay for 1 pizza, but you can order whatever else you like. It will only pay for the one pizza for the shop. If you have a BOGO coupon, you can use it, or any other deals that you can combine but just know that the company is only going to pay ya for your pizza for your shop up to $25 and they have their ways of confirming the pizza cost and will only pay that.
I frequently get the breadsticks+pizza deal without issue, but they do only reimburse about $16 on the shop instead of the $18 with the breadstick deal. No issues and the scheduler doesn't have a problem with coupon for free stuff. Just get an itemized receipt and circle your one pizza cost on it.