Why does KNIPEX offer two different VDE series (yellow-red cover versus double-walled, red immersion)?

Insulated KNIPEX pliers

The double-red dipped handles come from times when it was not yet possible to manufacture two-component handles.
Energy suppliers, above all, were very interested in VDE pliers with a significantly different look than "normal" pliers, in order to rule out misuse.
Both versions, provided they are marked accordingly, are suitable for work on electrical systems without restriction.