I think the problem is because the folder a digital camera creates is usually called "DCIM" If you down load this and leave the name unchanged,then the next download will again be named "DCIM" and as you can't have two folders with the same name you are asked if you want to overwrite the previous one.
The solution is to rename the folder each time after you download it.
You could copy the folder to your desktop,right click on it,scroll down to the "rename" entry left click that.The folder name can then be renamed to something(perhaps a date,or short reference to the contents,so DCIM might become 221107,taking todays date as an example.If you follow this routine each time the problem won't occur