Actually it would make perfect sense. I mean it could be an early model. Might even be the same manufacturer. Think about it: An earlier model designed for combat. Later replaced with models designed for combat. The early version not being adaptable as much, gets relegated to more simple tasks. Then becomes better known for the simpler tasks. The manufacturer stops making military grade and focuses on civilian models. Streamlining and trimming down the fat. removing armor plating. toning down heavier hydraulics for light weight, cheaper computer with simpler technology, using composites and light alloys, until you end up with a small light efficient and less combat ready.
Not near as bad as the G0T0 thing which was almost a direct copy of a later droid.