Is this normal and safe?
A disk image (or rom) can contain more data than actual file contents.
The 1.13 GB may refer to the sum of all file sizes, but the image itself may contain additional data (like the list of files, information where each file is located in the disk image). and other things. Often a disk/rom image can contain a lot of empty space, when the image is a 1:1 copy of something - for example a game may be 25 MB in a 32 MB cartridge, so you get a 32 MB image with the last 5 MB or so of empty/blank characters
Either way, the emulator will take it or not, it's not like it can infect your computer, since it's different architecture, different everything, the contents is read by the emulator and you get stuff on the screen or you don't get anything.
If the image is corrupted/broken at some point, the emulator will probably crash.
