Installing Security Update 10.13.6 twice?

[technano]

Hi there, I'm currently experiencing a very weird situation.

I have installed 10.13.6 once, right after a fresh install of High Sierra from my Bootable USB.

After a successful installation, I shut it down and turn it on again. And, it went into an installer page, telling me that macOS installation has failed.

I restart it, and press option and I see 2 boot option. macOS Installer and another is my own SSD. I select my own SSD and it boots in.

I checked Updates, and it shows that 10.13.6, which I have just installed is now required to download again?

Question: Why do I need to install it twice? It it because my MBP has dual graphics card? 1 is Nvidia, another is Intel.

I have never encountered this with my other Macbook, which all have single graphics card.

Would appreciate any input. Thanks!

 

[Mejoco_LC475]

See here, similar issue thread:

https://forums.macrumors.com/thread...update-2018-002-10-13-6-wont-install.2151143/

 

[technano]

Thanks for the replies.

I have since moved on with this issue. I did contacted Apple hotline with regards to this. The genius didn't gave me a satisfactory answer, but I just hmm alright.

I checked with my MacBook Pro 2015, my daily macbook. apparently, there are also some security updates that was installed more than once