josh ,can they do that considering they are offering 5 destinations form dsa

Yup it is possible. See below

DSA Based
06:20/08:25 DSA FAO/PRG 09:20/11:30
09:55/12:00 FAO/PRG DSA 12:55/13:05
13:50 DSA AMS 16:05

LPL Based
16:40 AMS DSA 16:55
17:20 DSA BCN/PMI 20:50
21:25 BCN/PMI DSA 23:00

The plane switches at AMS to allow a new crew to night stop each night. It is a way for easyJet to beat setting up a crew base at the airport, but if these routes prove well, then that will inevitably happen.