If your using KDE you need to modify the ALT key behaviour

Open Control Center --> Desktop --> Window Behaviour --> Actions

And change the modifire to key to something else

Validation plugin

Ensure the validation plugin display is visible by either clicking on the Blue Check Box on the left menu or typing Alt-V to toggle the display

To remove overlapping ways:

When you expand and highlight the over lapping nodes the over lapping ways should turn blue Hit the D key to remove the offending way

If the wrong way is deleted type ctrl-Z to undo the delete operation To switch to the the "other" way

Middle click on the blue way this will hopefully show multiply ways Hold down the ctrl key this will hold the way list open so you can release the middle mouse button Continue holding the ctrl key down and mouse over the next way description and left click on it's description Then hit the "D" key to delete the way

You may need to recreate part of the way if the overlapping way