My icon set doesn't match the size of the internal icons

Have decompiled the DO Internal Icon Set (Flat) into separate images with filenames as icon names, this allows me to add new icons and recompile as a separate set using montage.exe, I have used the standard 2 sizes 22px and 32px but there seems to be a difference between the 2 sets. In the SS the top icon is from the new set and the 2nd icon from the original DO (Flat) set, as you can see although they are both using the 22px image they are not the same size.
Have I got the sizes wrong ?

here is SS of the larger 32px set

I can't think of any reason to do that. Icon sets don't need to include all icons, just the ones you want to add or replace. The other icons can still come from another icon set (e.g. the internal set).

Either the icon sizes or the XML are wrong. Difficult to say without being able to see your XML.

System DPI can also play a part, as icons will be assumed to be standard DPI and scaled up for high DPI screens unless the XML specifies otherwise.