X-ray uncovers hidden portrait beneath famed Degas painting

So?

What is the conclusion of all this fastidious, expensive, introspective analysis;

to confirm painters paint over unfinshed canvasses??? or to confirm painters change their minds???

As a painter( of humble abilities), such actions are constant and even necessary due to financial constraints.

It is not uncommon for artists to paint over their works today too. Canvas is expensive.