It can happen when a woman is pregnant with fraternal twins and one embryo dies during the early stage of the pregnancy and the other embryo absorbs it’s twins cells.
What if the twins are monozygotic rather than fraternal? Then the person has two sets of DNA - his and his twin's - but those two sets are identical! I guess it's not a chimera then.
But yeah it's an interesting and kinda funny topic!
Wow, I love this question, it's an awesome guess indeed.
From studies, identical twins has same sets of DNA, but some environment and conditions can affect the way they're presented in reality.
So for your question, even if it's possible to have a chimera from monozygotic twins, the change/difference will definitely not be significant