Why would someone want to? If they want a leo with great markings all they'd have to do is go out and get one.
Although I do have to admit, I'd like to do something of the sort with uromastyx.
I'd like to see what happens when you breed an Egyptian uro with an ornate uro (egyptians get about 3 feet in length, ornates get about a foot and a half but are blue or green in color).
This is an ornate:

This is an Egyptian uro:

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2 Mali Uromastyx-Ares & Apollo
2 Bearded Dragons- Draco & Hades
1 Saharan Uromastyx-Iris
1 Leopard Gecko-Kalypso
1 Tokay Gecko-Sid Vicious
1 Tarantula-Peter Parker
1 Amazon Red Head Parrot-Pancho
1 African Gray Parrot-Keya
1 Dog-Cheeka
3 Fish-no names
1 Beta Fish-also no name
1 Zebra Finch-Beeps