ExamEval
Item Writing Flaws
Duplicate Question

Duplicate Questions on Multiple-Choice Assessments

By Sean P. Kane, PharmD, BCPS

Published June 14, 2025

A duplicate question on an exam occurs when two or more exam questions have identical or nearly identical language. When students encounter the same question multiple times within a single exam or across related assessments, it artificially magnifies the weight of certain content areas while reducing the overall validity and reliability of the measurement.

In addition to giving disproportionate weight to duplicated content, duplicate questions can also confuse students or encourage them to "game" the exam. For example, students might deliberately submit different answers to repeated questions, hoping to secure partial credit rather than risk losing all points by answering both the same way and getting them wrong.

Critical Issue

Duplicate questions compromise the principle of independent measurement. Each question on an exam should be an independent assessment of a student's knowledge. When questions are duplicated, the exam is no longer a valid measure of the student's overall understanding of the content domain.

Why Duplication Occurs

In nearly all cases, exam writers do not intentionally add the same or nearly the same exam question multiple times. This inadvertent error is usually due to:

Large Question Banks: When creating exams from large item banks, it is easy to accidentally select the same question twice, especially if the bank is not well-organized or if questions are not uniquely identified.
Bias Toward Specific Concepts: If a specific concept or question type is important to an instructor, they may inadvertently draft the same or similar questions when creating a large set of exam questions.
Team-Based Exam Creation: When multiple faculty members contribute questions to an exam, they may unknowingly submit similar items, leading to duplication if there is no cross-checking process.

Example of Duplicate Questions in Health Sciences Education

The following illustrates how two questions might assess nearly identical content, which is problematic if both appear on the same assessment. The "improved" version shows a question on a related, but distinct, concept.

Flawed Question

Question 15: A patient taking warfarin should avoid which of the following foods due to high vitamin K content?

A. Spinach and kale ✓

B. Oranges and grapefruits

C. Chicken and fish

D. Rice and pasta

This question appears as written. Later in the same exam...

Flawed Question

Question 42: Which food should patients on warfarin limit due to vitamin K interactions?

A. Leafy green vegetables ✓

B. Citrus fruits

C. Lean proteins

D. Whole grains

This is essentially the same question with minor wording changes. Both assess identical knowledge about warfarin-vitamin K interactions, giving this topic disproportionate weight in the exam while reducing coverage of other important anticoagulation concepts.

Impact on Exam Quality and Validity

Question duplication reduces exam quality and validity in several ways:

The weight of the duplicated content is inflated because the same concept is tested multiple times.
Internal consistency scores or metrics, such as KR-20 scores, discrimination index, or point biserial, are usually inflated simply because the same question is tested multiple times.
Other topics or concepts are less likely to be tested, which causes assessment under-representation of other topics.
Students who do not know the duplicated concepts are incentivized to answer differently between the questions in order to earn partial credit instead of no credit.

Preventing and Detecting Duplicate Questions

Examination blueprinting is one method faculty can use to ensure that their assessments align with intended student learning objectives and help prevent duplication (Ray 2018). The blueprinting process outlines how long an exam should be, the number of questions overall, the number of questions per topic, and potentially which learning objectives or concepts will be tested. The blueprint should guide item allocation and weighting so that each content area is represented appropriately, reducing the chance of accidental duplication.

Duplicate questions are best identified through an exam peer review process. If a faculty peer review is not feasible due to time or resources, an AI-assisted exam review platform like ExamEval can automatically detect duplicate or overlapping questions. ExamEval helps educators eliminate item-writing flaws, increase assessment reliability, and improve student learning outcomes with expert AI analysis.

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