is there a term for graphics which can replace each other's sections or parts and result in two new graphics?
The surrealist technique of combining sections of different images in order to create a unique composition is referred to as "Exquisite Corpse" or "Cadavre Exquis" (Ambrose &amp; Harris, 2011). By aligning the sections creatively or along a similar outline, one can achieve very unexpected results, as in the following example



In these cup designs by Chloe Lee Carson, sections of different illustrations have been combined to create unique characters.
Note that despite the name of this technique, Cadavre Exquis is not limited to animal or human imagery. In fact, it began as a word game where sentences were constructed in a similar unxexpected fashion. According to the Tate website, the technique's name is derived from one of the first games that resulted in: ‘Le cadavre exquis boira le vin nouveau’ (‘The exquisite corpse will drink the young wine’).



Reference:
Harris, P. &amp; Ambrose G. (2011), Basics Design 02 - Layout, AVA Publishing