Should you get condensation on the inside of double glazed windows?

The seal between the panes has failed, so don't try to repair it, it's cheap enough to replace.

Modern double paned windows are sealed with a gas called argon inside.The gas resists heat transfer.

When the seal fails, there is gas and air inside.The water condenses when there is a disparity between indoor and outdoor temperature.

If you want a new sealed glass assembly, you can get it from a glass dealer who can measure the unit, make the assembly and install it.I recently had 3 assemblies replaced for around $575 which were all three appx 36" x 36" with decorative cross pieces inside the panes.

The seal has broken.These can't be fixed.The window is assembled in a factory.

You'll never recover the performance that you used to have if you take the unit out and patch it on a hot and dry day.

When double glazed is 10 to 15 years old, it happens because the seals have broken.You can replace the seals, but this is only a temporary solution.It makes sense to replace the whole unit.