On Windows: open Paint. Or, even better, GIMP - which also works on Linux.
Right click on first image, choose 'copy'
Go to image editor (Paint/GIMP), press <cntrl><V> (paste)
Right click on second image, choose 'copy'
Go to image editor, press <cntrl><V>, slide newly inserted image around to get it to fit nicely with the first image you have just inserted.
Save result.
GIMP will allow you to modify the new image even more. Enhancing contrast would be my first choice with this image. Enjoy.
Thank you for posting the image, the Hart family has many members. Nice to see them all in one table.