`ctx.set_fonts()` Doesn't Apply Fonts with Same Name

If a font file named `my_font` is set using `ctx.set_fonts()` and then another font file with the same name is set again using `ctx.set_fonts()`, it won't be applied.

Additionally, it's recommended to apply fonts immediately using `ctx.set_fonts()`.

Start by locating the implementation of ctx.set_fonts() and trace how a font named my_font is handled when it is registered twice. Reproduce the reported behavior with two font files using the same name, then verify that the later call is applied immediately and that the documented recommendation is satisfied.

Written by the indexing model from the issue text.