When you open a INX file in TagEditor the whitespaces get duplicated

This happens when using a non-OS font in the InDesign file.  To prevent this from happening, you should go into the Filter Settings (Start->All Programs->SDL TRADOS 7->Filters) and untick the "Show Display Formatting" box.
This will lead to all text being shown as Arial in TagEditor. However the final InDesign file will still be in the [...]