Yes, it'll get all mixed up.
The Hagen GLO's have much better reflectors than the Coralife T5 HO's, so will get more light into the tank, if that makes a difference to you. Bulb choice are personal preference partly, once you have met the plant requirements. I'm not currently running T5 HO's (just the NO Coralife's for now and PC lights) so I'll let others give you advice on that.
Would this:
http://www.petsmart.com/product/index.jsp?productId=3060839&clickid=cart
be the GLO light you're talking about?
From their description, I can't figure out if this is a 36 or 48" light, from the description is both:
Highly attractive Glo T5 HO (High Output) Systems were developed for both marine and freshwater systems to direct maximum lighting to your aquarium. Due to the compact diameter of the T5 HO bulbs, up to two of these powerful bulbs can now be housed in the same space that one T8 or T10 requires, providing substantially greater light levels and reducing space requirements at once. The combination of the space saving design, energy efficiency and easy installation make the T5 HO System ideal for aquarists of all levels from the novice to the hobbyist.
This
36" Glo T5 HO Lighting System features a 39 watt high output format and a double light configuration. Integrated extension brackets adapt to a range of aquarium lengths (46.75" - 64"). The lighting system includes aquarium mounting brackets for a secure installation and vertical adjustments. In addition, the fixture includes mounting legs with adjustable heights. This assists in adjusting aquarium light levels as well as providing a variety of visual presentations. Water-resistant end caps provide safe, reliable performance that is made to last throughout the years.
The system includes a T5 HO electronic ballast, and polished internal aluminum reflector all housed within the polished aluminum canopy with integrated hanging and extending mounting brackets. Bulbs sold separately.
Product Features:
* Integrated Extension Brackets
54 watt unit adjusts to fit aquariums from 46.75 to 64 inches in length.
* Aquarium Mounting Brackets
Allows the fixture to be fastened to the aquarium at four different vertical positions and assists in adjusting the light levels.
* Integrated Suspension Tabs
Enables easy suspension over your aquarium but if not used they recess into the fixture ensuring a clean attractive look.
* Electronic Technology
Creates optimal bulb performance and longevity of the lamp and ballast.