what's the term for double window in one window frame and why is it considered outdated technology?
Sounds like you're talking about "triple-track storm windows", which usually has 3 panels, 2 with glass, one with a screen; in the summer you slide the bottom glass panel up, and screen down; in the winter you slide it down. They were commonly retrofitted to older houses that had no storm windows.

Newer windows (the windows themselves, not the storm windows) usually have two glass panels with a vacuum or gas in between, eliminating the need for bolted on storm windows. The newer windows, besides being more energy efficient, also can block UV rays that damage curtains and furniture.

The reality is there's a lot of cheaply made windows out there that look modern, but transmit sound like a hollow steel drum; and properly maintained triple tracks can be almost as energy efficient.