May be difficult to found, because Rotala Butterfly is not any stable form.
All these plants are Rotala Butterfly Mini:
The problem with those Butterfly is that just only little changes can result in "forever Green plants".
Once a Butterfly morph back to Macrandra Green - it will never again get magenta color.
Can be a very frustrating plant.
Better look for Rotala Macrandra Mini Type IV "Red":
This tiny Macrandra can be red or magenta, but this is a stable form that will not morph back to Macrandra Green.