DIstance - Duplicated split distance expense shows the original amount

[lanitochka17]

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Version Number: 9.3.8-0
Reproducible in staging?: Yes
Reproducible in production?: N/A - new feature, doesn't exist in prod
If this was caught during regression testing, add the test name, ID and link from BrowserStack: #77758
Email or phone of affected tester (no customers): soidjisojdnsoijsdosj@gmail.com
Issue reported by: Applause Internal Team
Bug source: Exploratory - Significant User Experience Deterioration
Device used: Mac 26.1 / Chrome
App Component: Money Requests

Action Performed:

1. Go to staging.new.expensify.com
2. Go to workspace chat.
3. Create a manual expense.
4. Open the manual expense.
5. Click More > Split > Save.
6. Open any split manual expense.
7. Click More > Duplicate.
8. Open the duplicated split manual expense.
9. Click Amount.
   → The duplicated split manual expense is not considered the split. The amount is the same as the split amount.
10. Create a distance expense.
11. Open the distance expense.
12. Click More > Split > Save.
13. Open any split distance expense.
14. Click More > Duplicate.
15. Open the duplicated split distance expense.
16. Click Amount.

Expected Result:

• The duplicated split distance expense will not be considered as split, just like duplicated split manual expense.
• Amount will be the same as the split.

Actual Result:

• The duplicated split distance expense is considered as split.
• Amount is the original of the split.

Workaround:

Unknown

Platforms:

• Android: App
• Android: mWeb Chrome
• iOS: App
• iOS: mWeb Safari
• iOS: mWeb Chrome
• Windows: Chrome
• MacOS: Chrome / Safari

Screenshots/Videos

Bug7056758_1769207428202.3.mp4

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[melvin-bot]

You have been assigned to this deploy blocker because you recently merged this PR: #77758

[melvin-bot]

💬 A slack conversation has been started in #expensify-open-source

[melvin-bot]

Triggered auto assignment to @bfitzexpensify (Bug), see https://stackoverflow.com/c/expensify/questions/14418 for more details. Please add this bug to a GH project, as outlined in the SO.

[github-actions]

👋 Friendly reminder that deploy blockers are time-sensitive ⏱ issues! Check out the open `StagingDeployCash` deploy checklist to see the list of PRs included in this release, then work quickly to do one of the following:

1. Identify the pull request that introduced this issue and revert it.
2. Find someone who can quickly fix the issue.
3. Fix the issue yourself.

[OSBotify]

Investigation Summary

Classification: Frontend bug
Causing PR: #77758 - Duplicate Expenses Add Distance Expense Support by @jjcoffee (High confidence)
Related Issues: None

Recommendation: REVERT

This PR introduced support for duplicating distance expenses, but it did not properly handle the case where the distance expense being duplicated is itself a split expense. The bug causes duplicated split distance expenses to retain their split status and show the original amount instead of the split amount.

Labels: Keeping DeployBlockerCash. This is a frontend bug affecting the App deploy. No label changes needed.

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Detailed Analysis

Evidence:
PR 77758 was merged on 2026-01-23 at 12:44:06Z and added distance expense duplication support. The issue was reported on 2026-01-23 at 22:45:23Z (10 hours later) and is reproducible on staging v9.3.8-0, which includes this PR.

The issue specifically states:

• Duplicating a split manual expense works correctly: the duplicate is not considered a split and shows the split amount
• Duplicating a split distance expense works incorrectly: the duplicate IS considered a split and shows the original amount

This asymmetry confirms the bug was introduced by the distance expense duplication feature in PR 77758.

Verification:
I verified that PR 77758 added the distance expense duplication code path in src/libs/actions/IOU/Duplicate.ts lines 565-587. This code passes transaction.comment directly to existingTransaction (line 572). For split expenses, transaction.comment contains originalTransactionID and source split which then gets merged into the new transaction, making it be treated as a split expense with the original amount.

Root Cause:
When duplicating a distance expense in Duplicate.ts, the code passes the entire transaction.comment object which includes split information (originalTransactionID and source). This is then merged into the new transaction via fastMerge in IOU/index.ts line 3201, causing the duplicate to incorrectly be treated as a split expense. Manual expenses do not go through this code path, which is why they work correctly.