Doing flat bench or inclines? Pain in both shoulders and only when doing bench/inclines? Only with DB's, not BB's? Sound like you may workout at home.
Do not know if we are being played by this question, but responding anyway:
Pretty simple process, just sit on the end of the bench (for example) bend over and heave/pull the DB's up using the whole upper body. Not just arms involved in this action. You are actually cleaning both DB's high enough to let you fall back on the bench with the DB's coming to rest in the starting pressing position. When DB's become heavier you might have to use the kick-up or standing method. Let me know when you are ready for that.
Pain suggest something may require attention if it happen every time with DB's. A more favorable warm-up time may be needed, with the focus on stretching. Good Luck.