diff --git a/src/components/ChallengeEditor/ChallengeReviewer-Field/index.js b/src/components/ChallengeEditor/ChallengeReviewer-Field/index.js
index 288d4d1f..5fbafd29 100644
--- a/src/components/ChallengeEditor/ChallengeReviewer-Field/index.js
+++ b/src/components/ChallengeEditor/ChallengeReviewer-Field/index.js
@@ -444,41 +444,6 @@ class ChallengeReviewerField extends Component {
 
     const isAIReviewer = this.isAIReviewer(defaultTrackReviewer)
 
-    // Prevent adding a second manual (member) reviewer for the same phase.
-    // If the default phase already has a manual reviewer, attempt to find another
-    // suitable review phase that does not yet have a manual reviewer and use it.
-    if (!isAIReviewer && defaultPhaseId) {
-      const existsManualForPhase = currentReviewers.some(r => (r.isMemberReview !== false) && (r.phaseId === defaultPhaseId))
-      if (existsManualForPhase) {
-        const possibleAlternatePhase = (challenge.phases || []).find(p => {
-          const rawName = p.name ? p.name : ''
-          const phaseName = rawName.toLowerCase()
-          const phaseWithoutHyphens = phaseName.replace(/[-\s]/g, '')
-          const acceptedPhases = ['review', 'screening', 'checkpointscreening', 'approval', 'postmortem']
-          const isSubmissionPhase = phaseName.includes('submission')
-          const acceptable = acceptedPhases.includes(phaseWithoutHyphens) && !isSubmissionPhase
-
-          if (!acceptable) return false
-
-          const phaseId = p.phaseId || p.id
-          const used = currentReviewers.some(r => (r.isMemberReview !== false) && (r.phaseId === phaseId))
-          return !used
-        })
-
-        if (possibleAlternatePhase) {
-          defaultPhaseId = possibleAlternatePhase.phaseId || possibleAlternatePhase.id
-          if (this.state.error) this.setState({ error: null })
-        } else {
-          const phase = (challenge.phases || []).find(p => (p.id === defaultPhaseId) || (p.phaseId === defaultPhaseId))
-          const phaseName = phase ? (phase.name || defaultPhaseId) : defaultPhaseId
-          this.setState({
-            error: `A manual reviewer configuration already exists for phase '${phaseName}'`
-          })
-          return
-        }
-      }
-    }
-
     // For AI reviewers, get scorecardId from the workflow if available
     let scorecardId = ''
     if (isAIReviewer) {
diff --git a/src/components/ChallengeEditor/index.js b/src/components/ChallengeEditor/index.js
index da51eb04..6516403f 100644
--- a/src/components/ChallengeEditor/index.js
+++ b/src/components/ChallengeEditor/index.js
@@ -897,11 +897,47 @@ class ChallengeEditor extends Component {
     return !(isRequiredMissing || _.isEmpty(this.state.currentTemplate))
   }
 
+  // Return array of phase names that have more than one manual (member) reviewer configured.
+  // If none, returns empty array.
+  getDuplicateManualReviewerPhases () {
+    const { challenge } = this.state
+    const reviewers = (challenge && challenge.reviewers) || []
+    const phases = (challenge && challenge.phases) || []
+
+    const counts = {}
+    reviewers.forEach(r => {
+      if (r && (r.isMemberReview !== false) && r.phaseId) {
+        const pid = String(r.phaseId)
+        counts[pid] = (counts[pid] || 0) + 1
+      }
+    })
+
+    const duplicatedPhaseIds = Object.keys(counts).filter(pid => counts[pid] > 1)
+    if (duplicatedPhaseIds.length === 0) return []
+
+    return duplicatedPhaseIds.map(pid => {
+      const p = phases.find(ph => String(ph.phaseId || ph.id) === pid)
+      return p ? (p.name || pid) : pid
+    })
+  }
+
   validateChallenge () {
     if (this.isValidChallenge()) {
+      // Additional validation: block saving draft if there are duplicate manual reviewer configs per phase
+      const duplicates = this.getDuplicateManualReviewerPhases()
+      if (duplicates && duplicates.length > 0) {
+        const message = `Duplicate manual reviewer configuration found for phase(s): ${duplicates.join(', ')}. Only one manual reviewer configuration is allowed per phase.`
+        this.setState({ hasValidationErrors: true, error: message })
+        return false
+      }
+
+      if (this.state.error) {
+        this.setState({ error: null })
+      }
       this.setState({ hasValidationErrors: false })
       return true
     }
+
     this.setState(prevState => ({
       ...prevState,
       challenge: {