Miralax vs dulcolax balance?

I work at a Gastro office. Our doctors recommend a ton of Miralax for colonoscopy preps and constipation. It's an OTC product of PEG 3350. I noticed in our sample cabinet we have a ton on Dulcolax Balance samples and coupons and it appears to be the same as Miralax; PEG 3350. We have no samples of Miralax or coupons and a search of CVS showed the Dulcolax product to be cheaper. Before i show this to management (in an effort to save patient's money) can anyone confirm for sure that the two are the same?