Partitions

So I have been trying to get my head around partitions. On checking my system (128 GB ssd with my os on it and a 1TB ssd where I store everything). I had a look at my system via gparted. It shows that there is a boot/efi partition dev/sda1 of 512 mb.
There is an extended partition dev/sda2 of 118.74 gb and then an ext4 dev/sda5 partition again 118.74 gb.

The partitioning was done as part of the install and I haven't changed anything and the system is working fine.

I don't understand how 2 partitions dev/sda2 and dev/sda5 can both occupy the same amount of disk space.

Can anyone advise if this is an acceptable way for the system to operate or do I need to make changes?

I have tried to upload a screen print of gparted but not sure if it has worked. I hope my explanation makes sense.

Yes, it is perfectly acceptable and safe.

That is because the concept of an Extended Partition is pretty confusing all on its own.

An Extended Partition was developed as a means of overcoming the MBR (Legacy Boot) Limit of handling only up to Four Bootable Partitions.

An Extended partition acts as a Container for Logical Partitions. You can have multiple Logical Partitions contained within the container of the bootable Extended partition. This allows the ability to have greater then Four Bootable Partitions on an MBR system by having some of them contained in One.
The development of EFI and EFI with GPT (GUID Partitioning Table, not Chat...) renders all of the above obsolete. With EFI GPT, a user could reasonably have as much as 256 bootable partitions (Ignore Internet claims that it allows an Infinite amount, that is not really accurate to Physics). But until EFI GPT boot, the Extended Partitions provided a nice workaround.

The necessity of the workaround:
Early on, Windows and manufacturers both wanted to grasp control of Recovery Partitions in order to have a competitive edge in the market. With each vying for dominance over the Partitions, a computer being marketed for sale could easily end up with the majority of available partitions gobbled up and the user stuck with only one usable bootable partition. This would make the user pretty unhappy and defeat the purpose of having a marketing edge by offering the other services that the partitions were eaten up by.
It was a catch-22 and the Extended Partition gave them a handy Catchers Mitt to employ.

Your extended partition contains only your one logical partition and so - the amount of space allocated on the disk is the same amount. They both occupy the same space without any other partition to claim some of that Extended Partition space.

Thank You.