In fact, from "1" up and from "1" down, they are not equal.

Depreciation of 20% is1-0.2 = 0.8; An increase of 20% means 1+0.2= 1.2, which is different from the original value "1",1/0.8 =1.25; And 1.2/ 1= 1.2.

This creates what you call a contradiction.