How is the development of the cell theory by Matthias Schleiden and Theodor Schwann an example of multiple approaches yielding the same result

Matthias Schleiden (1804-1881) and Theodor Schwann (1810-1882) were two German scientists, who are credited with the development of cell theory. Cell theory is the idea that all living organisms are made up of cells. It has three main tenets:

All living organisms are composed of one or more cells. The cell is the basic unit of structure and organization in organisms. Cells can only arise from pre-existing cells.

In 1839, Schleiden suggested that all plants are made up of cells or of the result of cells. In the same year, Theodor Schwann stated that along with plants, animals are composed of cells or the product of cells. Although the approach each of them followed involved different living organisms, they were both able to arrive to the same conclusion.