That looks like the same account twice. Is it?

Also, please post your Troubleshooting Information. At the top right of the Thunderbird window, click the menu button ≡, then select Help > Troubleshooting Information. Press the "Copy text to clipboard button" and paste the information into your reply.

Hi, Thank you for your reply, I think you are correct - same account twice. Cut and past below. I had to trim the end of the post, too long for system. Application Basics

   Name: Thunderbird
   Version: 102.6.1
   Build ID: 20221219215418
   Distribution ID:

   Update Channel: release
   User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.6.1
   OS: Windows_NT 10.0 19045
   OS Theme:

   Launcher Process: Enabled
   Multiprocess Windows: 0/0
   Fission Windows: 0/0
             Enabled by default
   Remote Processes: 3
   Enterprise Policies: Inactive
   Google Location Service Key: Missing
   Google Safebrowsing Key: Missing
   Mozilla Location Service Key: Missing
   Safe Mode: false
   Memory Size (RAM): 15.9 GB
   Disk Space Available: 1,676 GB

 Mail and News Accounts
   account1:
     INCOMING: account1, , (pop3) pop3.zen.co.uk:110, 0, passwordCleartext
     OUTGOING: , mail.zen.co.uk:587, alwaysSTARTTLS, passwordCleartext, true

   account2:
     INCOMING: account2, , (none) Local Folders, 0, passwordCleartext

   account3:
     INCOMING: account3, , (pop3) pop3.zen.co.uk:110, 0, passwordCleartext
     OUTGOING: , mail.zen.co.uk:587, alwaysSTARTTLS, passwordCleartext, true

 Calendar Settings

     Home

       Name
       Value

       Name:
       Type: storage
       Disabled:
       Username:
       URI:
       Refresh Interval:
       Read-only:
       Suppress Alarms:
       Cache Enabled:
       iMIP Identity: id1
       iMIP Disabled:
       iMIP Account:
       Organiser Id:
       Force Email Scheduling:
       Popup Alarms Supported:
       Alarms on Invitation Supported:
       Max Alarms Per Event:
       Attachment Supported:
       Max Categories:
       Privacy State Supported:
       Priority Supported: true
       Event Supported:
       Task Supported:
       Local Time Supported:
       UTC/GMT Supported:
       Auto-Scheduling Supported:

       URI:
       Refresh Interval:
       Read-only:
       Suppress Alarms:
       Cache Enabled:
       iMIP Identity: id1
       iMIP Disabled:
       iMIP Account:
       Organiser Id:
       Force Email Scheduling:
       Popup Alarms Supported:
       Alarms on Invitation Supported:
       Max Alarms Per Event:
       Attachment Supported:
       Max Categories:
       Privacy State Supported:
       Priority Supported: true
       Event Supported:
       Task Supported:
       Local Time Supported:
       UTC/GMT Supported:
       Auto-Scheduling Supported:

 Crash Reports for the Last 3 Days

 Remote Processes

   Type: Count

     Web Content: 1 / 8
     Extension: 1
     GPU: 1

 Add-ons

     Name
     Type
     Version
     Enabled
     ID

       Amazon.co.uk
       extension
       1.1
       true
       amazon@search.mozilla.org

       Bing
       extension
       1.0
       true
       bing@search.mozilla.org

       Chambers (UK)
       extension
       1.0
       true
       chambers-en-GB@search.mozilla.org

       DuckDuckGo
       extension
       1.0
       true
       ddg@search.mozilla.org

       Google
       extension
       1.0
       true
       google@search.mozilla.org

       Grammar & Spell Checker — LanguageTool
       extension
       6.0.5
       true
       languagetool-mailextension@languagetool.org

       Wikipedia (en)
       extension
       1.0
       true
       wikipedia@search.mozilla.org

 Security Software

   Type: Name

     Antivirus: Avast Antivirus
     Antispyware:
     Firewall: Windows Firewall

 Graphics

     Features
     Compositing: WebRender
     Asynchronous Pan/Zoom: wheel input enabled; scrollbar drag enabled; keyboard enabled; autoscroll enabled; smooth pinch-zoom enabled

They look the same in Troubleshooting Information as well. I have no idea how you managed to create two identical accounts.

First off all, create a full backup of your Thunderbird profile. https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data#w_backing-up-a-profile

Then check which of the two accounts has your email history. The newer one should have no email history, but only a few messages which were received by in both. If so, I'd just delete the newer account.

Hi, I took a risk and didn't back-up, but found out how to delete the second account without significant emails. It left me with 2 x deleted and outboxes (see screen shot), but I can live with that. Couldn't see how to delete them. At least I am not hitting my ISP twice to collect the same emails. Thank you very much for your help. It really is appreciated. Kind regards, Alan

It left me with 2 x deleted and outboxes (see screen shot)

The Local Folders account is always there. If you don't use it, just leave it alone. However, you also created a nested 'Local Folders' folder underneath the Local Folders account. Assuming there are no messages in that nested 'Local Folders' folder you can probably delete that as well.

Thank you. Alan