Nah, this post's phrasing is misleading. Chimerism comes from a fusion of two separate embryos, not from two fully-formed babies merging together. A chimera is less one dominant embryo that "absorbs a twin," and more a regular person that just happens to be made up of two separate sets of genetic material. Imagine having two different puzzles with pieces that are cut in an identical pattern. You could use pieces from either puzzle to fit into each other. If you randomly draw pieces from either set and merge them into one picture, you end up with a puzzle that's a bit of both, but still only one. That's how it works with chimeras - the DNA from two individuals are mixed and matched to create a patchwork of both in one body. A key difference is, a puzzle would have leftover pieces - but the body would not.

It's often not apparent in any way. However, if the two sets of DNA call for different skin colors or something, a chimera might show both colors in different areas.

In the post's case, the cells that went on to make the man's testicles were made with different DNA than whatever part the first sample was taken from. There may be more parts of his body that use that same DNA, but unless they test a sample from every part of him, we'll never know exactly.