It’s true that the same amount of data is being download, but take in account that download can be parallel. The http protocol for example states that you can have x amount of parallel download. And thats why websites squash JS and CSS into one file.
More paralell downloads mean greater saturation of the bandwidth.
I don’t know if this applies FiveM, if this is the case then having 25 resources would be faster then 50 download. But that’s a big “if” wether this applies.