Unable to copy EFI folder into the EFI partition (partition can be only read)

I'm following this guide and after running ./MountEFI.command i get this options

1. Install macOS Big Sur (disk2s1)
2. Macintosh HD (disk1s1)
3. Shared Support (disk3s1)
4. Shared Support (disk4s2)

Firstly I don't get why I have two options with the same name, and that nameSecondly I don't understand why after choosing one of them, the mounted partition is only readable.

Here my diskutil list

/dev/disk0 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *500.3 GB disk0
1: EFI EFI 314.6 MB disk0s1
2: Apple_APFS Container disk1 500.0 GB disk0s2

/dev/disk1 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +500.0 GB disk1
Physical Store disk0s2
1: APFS Volume Macintosh HD 11.2 GB disk1s1
2: APFS Volume Macintosh HD - Data 286.3 GB disk1s2
3: APFS Volume Preboot 82.1 MB disk1s3
4: APFS Volume Recovery 528.9 MB disk1s4
5: APFS Volume VM 21.5 GB disk1s5

/dev/disk2 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *128.3 GB disk2
1: EFI EFI 209.7 MB disk2s1
2: Apple_HFS Install macOS Big Sur 128.0 GB disk2s2

/dev/disk3 (disk image):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme +13.2 GB disk3
1: EFI EFI 209.7 MB disk3s1
2: Apple_HFS Shared Support 12.8 GB disk3s2