If this is a mirror, why the checksum is not the same from source forge?

[uilianries]

Hi! I was expecting to use this repository as a mirror from https://tclap.sourceforge.net/, but it seems like it is not a mirror, because the package files have different checksum.

wget https://sourceforge.net/projects/tclap/files/tclap-1.2.5.tar.gz
sha256sum tclap-1.2.5.tar.gz 
bb649f76dae35e8d0dcba4b52acfd4e062d787e6a81b43f7a4b01275153165a6  tclap-1.2.5.tar.gz

wget https://github.com/mirror/tclap/archive/refs/tags/v1.2.5.tar.gz 
sha256sum v1.2.5.tar.gz 
7e87d13734076fa4f626f6144ce9a02717198b3f054341a6886e2107b048b235  v1.2.5.tar.gz

As you can see, the SHA-256 is different from the original. Is there any reason for having this mismatch?