The two shots are not the same?
The two shots are the same. But, in some cases, the first shot may be priming the immune system to incorrectly attack the body’s own tissue following the second injection. In theory, this could also occur when a wild infection is encountered. It is not clear yet if this is a case of ADE (Antibody Dependent Enhancement), but it might be. If so, really bad news. Can also affect lung tissue and other organs.
“ADE can occur during the development of a primary or secondary viral infection, as well as after vaccination with a subsequent virus challenge.”
https://en.m.wikipedia.org/wiki/Antibody-dependent_enhancement