Sony's sticks are proprietary and outside what you read at Sony and such, the inner details are not published. But I have used the older sticks in newer devices that take the new sticks.
In short, it's my choice not to duplicate readily available web content. But the Sony stick issue is worth noting. Sony doesn't seem to want third parties to use their stick.
What is the difference between the old one and the Duo version? Also, does the T-1 only use the duo or can you use the older memory sticks as well?