Identify who made each source and what it actually says. Agreement on a detail can support that detail, but a source's opinion is not automatically shared by everyone.
Worked example
A dated ticket can support the date printed on it. A visitor's letter may describe a personal reaction. Those sources answer different parts of a historical question.
An Exhibition, Two Fictional Sources
Source A is a poster: 'Town exhibition opens June 12, 1912, at 10 a.m.' Source B is Ada's letter dated June 13, 1912: 'Yesterday was opening day. I arrived just after lunch. I liked the model train best, but I did not visit every room.' These sources were written for this exercise and are not real historical documents.