Continued from [Manual Partitioning - boot, esp flag]
You can have as many as you need and most often you only have one. Even if you are dual-booting several Linux distroes you can get along with one if the size is reasonable.
The problem manifests in dual boot sceanario which includes Windows.
In that case it an advantage to have two because Windows might change the $esp and you loose your Manjaro entry.
That issue can - to great extend - be avoided by having two $esp.
If you boot a live environment and select Detect EFI boot loaders option you will find that it contains entry like (hd0.gpt12) which refers to the loaders location on disk.
What theoreticly - in a Window-Linux dual-boot scenario - can cause issue with two $esp on same drive is when you decide to remove the Windows part and merge the partition with your root partiton. That would be impossible because you cannot move your second $esp without breaking your boot.
But that is a theoretical issue - as Linux does not care how the data is organized - only humans do.