Set Width/Height of 2-point curve select box

Hello,
I have one 2-point curve. In width field of root menu 71.695 mm
In height field of root menu - 25.623 mm

With square handlers i can change width and height values

But if i write values direct in width or height field, for example 70 for width and press Enter value for width return to 71.695 ?!

Then i repeat this sample and draw rectangle with size 100 x 50 mm 

Then write 20 mm in width field and press Enter. Width value remains 20

Why 2-point curve width or height box can not remain when enter values direct in width/height fields?

Greetings!