Not sure how it happened..... 2 Drives

[skippybangkok]

I am very sure I used to have one single 500GB drive, but it looks like I have 2 now,

 

can anyone tell me what I have done, and if there is a way to merge them without reformatting ?

 

Thanks

 

 

[sometimewoodworker]

11 hours ago, skippybangkok said:

I am very sure I used to have one single 500GB drive, but it looks like I have 2 now,

 

can anyone tell me what I have done, and if there is a way to merge them without reformatting ?

 

Thanks

you should with 99% certainly do nothing.
 

You almost certainly have a single drive,  however the newer Apple formatting allows it to show as 2 volumes. Look at the space available. 
If you bring up a utility like disk warrior you will see at least 4 volumes on your single drive. If however you created another volume or partition disk utility may allow you to delete or at least reduce the size of the second visible volume/partition. 
There are various views of the APFS depending on the system you are using.

the partitions/volumes may be different if you have upgraded rather than erase and fresh install.

these are different views there is only 1 Big Sur volume available despite there being 4 actually there.

 

[skippybangkok]

@sometimewoodworkerThanks for your reply. I suspected same disk as available space was exactly the same which would be a fluke if 2 different disks.

 

As such, will just leave it.