Deduplicates CheckIssue items on Code + Selector + File + Line, keeping the earliest TimestampSeconds when duplicates exist (VS-RND-5 Step 8).
CheckIssue
Code + Selector + File + Line
TimestampSeconds
Deduplicates
CheckIssueitems onCode + Selector + File + Line, keeping the earliestTimestampSecondswhen duplicates exist (VS-RND-5 Step 8).