Every camera has extended ISO. In the upper end where the ISO is pushed, I do not recommend using them.
But the extended low ISO is worth testing. In theory, the image quality should be better. The ISO is pulled and the brighter images get darker and that will reduce noise.
Check out the video to see my test on the different Olympus cameras.
Dual Card Slots in my Olympus OM-D E-M1 MkII are very handy for back up during image making. Memory Cards can fail. Having Dual Card Slots in your camera is very crucial. Especially if you do wedding photography and venues that are one time things. You cannot re-make the wedding. With camera recording to two memory cards you have a back up straight away. The if you have a memory card failure your images are not gone. You still have the other one with the images.