Diafero is right. There isn't no evidence at all that there is a different age. Looking in my dat folder of URU Live, I see only one garrison section. And with experience with Ae'gura in ABM where I removed blockers to make it more comfy , it is easy to remove or put back whole areas of an age with a simple mouse click playing in the SDL.
With the discovery made by Sirius, a friend of mine, we can actually go beyond limits in Hood's Gahreesen and it isn't looking at all like our own Gahreesen.
The accesible areas of the age is only part of the 1st building main floor. You can climb up the rumbles as everyone does it in own Gahreesen but, when up there, you just stare at emptyness . There isn't any 2nd floor and therefore, cannot access the control room to make the elevators and door openings functionning.
I have made 2 quests in MOULa, one for own Gahreesen and one for hood's Gahreesen, and in each I stated really early a warning to open the right quest in the right instance since they both are the same age. Some markers of own Gahreesen when opened up in Hood's Gahreesen are floating in black area since they just show up.