Still necessary for developers to delete all existing WebHelp files before updating?

Hello,

I'm using RoboHelp version 9.02 on my Windows 7 64-bit computer to generate a WebHelp project. Years ago, I was told to always ask developers to completely clear out the existing files in the WebHelp folder (on their end) before replacing them with updated files. In other words, when I compile the WebHelp project, I typically copy the output from the generated WebHelp folder on my hard drive, store it somewhere where a developer copies it, and then they do their magic with it on their end. I've always told them to delete the contents of the existing (older version) WebHelp folder on their end before copying in my new files. Does anyone know if this is still necessary?

I'm working with a different developer now and he just copies and pastes my newly generated files into his existing folder (without removing prior contents). Can this cause issues?

Thanks for your help.