diff --git a/.DS_Store b/.DS_Store
new file mode 100644
index 0000000..0cbf169
Binary files /dev/null and b/.DS_Store differ
diff --git a/.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata b/.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
new file mode 100644
index 0000000..919434a
--- /dev/null
+++ b/.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Workspace
+   version = "1.0">
+   <FileRef
+      location = "self:">
+   </FileRef>
+</Workspace>
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0952f49..65cd6bc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,12 @@ Bugfixes:
 
 - Strip byte order mark from all input strings, not just when loading files (#128) -- @Diggory
 
+## 0.8.2
+
+Bugfixes:
+
+- Throw an error when encountering duplicate column names in CSV headers (#136) -- @TomorrowMC
+
 ## 0.8.1
 
 Bugfixes:
diff --git a/SwiftCSV/Array+duplicates.swift b/SwiftCSV/Array+duplicates.swift
new file mode 100644
index 0000000..63bc027
--- /dev/null
+++ b/SwiftCSV/Array+duplicates.swift
@@ -0,0 +1,13 @@
+//
+//  Array+duplicates.swift
+//
+//
+//  Created by 胡逸飞 on 2024/4/26.
+//
+
+extension Array where Element: Hashable {
+    func duplicates() -> [Element] {
+        let counts = self.reduce(into: [:]) { counts, element in counts[element, default: 0] += 1 }
+        return counts.filter { $0.value > 1 }.map { $0.key }
+    }
+}
diff --git a/SwiftCSV/Parser.swift b/SwiftCSV/Parser.swift
index ac329ff..1bfc336 100644
--- a/SwiftCSV/Parser.swift
+++ b/SwiftCSV/Parser.swift
@@ -126,6 +126,12 @@ enum Parser {
     static func enumerateAsDict(header: [String], content: String, delimiter: CSVDelimiter, rowLimit: Int? = nil, block: @escaping ([String : String]) -> ()) throws {
 
         let enumeratedHeader = header.enumerated()
+        
+        // Check for duplicate column names
+        let duplicateColumns = header.duplicates()
+        if !duplicateColumns.isEmpty {
+            throw CSVParseError.duplicateColumns(columnNames: duplicateColumns)
+        }
 
         // Start after the header
         try enumerateAsArray(text: content, delimiter: delimiter, startAt: 1, rowLimit: rowLimit) { fields in
diff --git a/SwiftCSV/ParsingState.swift b/SwiftCSV/ParsingState.swift
index ed37ce0..74c0e95 100644
--- a/SwiftCSV/ParsingState.swift
+++ b/SwiftCSV/ParsingState.swift
@@ -9,8 +9,10 @@
 public enum CSVParseError: Error {
     case generic(message: String)
     case quotation(message: String)
+    case duplicateColumns(columnNames: [String])
+    
+    
 }
-
 /// State machine of parsing CSV contents character by character.
 struct ParsingState {
 
diff --git a/SwiftCSVTests/DuplicateColumnNameHandlingTests.swift b/SwiftCSVTests/DuplicateColumnNameHandlingTests.swift
new file mode 100644
index 0000000..6e539ee
--- /dev/null
+++ b/SwiftCSVTests/DuplicateColumnNameHandlingTests.swift
@@ -0,0 +1,64 @@
+//
+//  DuplicateColumnNameHandlingTests.swift
+//
+//
+//  Created by 胡逸飞 on 2024/4/27.
+//
+
+import Foundation
+import XCTest
+@testable import SwiftCSV
+
+class DuplicateColumnNameHandlingTests: XCTestCase {
+    
+    func testErrorOnDuplicateColumnNames() throws {
+        let csvString = """
+        id,name,age,name
+        1,John,23,John Doe
+        2,Jane,25,Jane Doe
+        """
+        
+        XCTAssertThrowsError(try CSV<Named>(string: csvString)) { error in
+            switch error as? CSVParseError {
+            case .duplicateColumns(let columnNames):
+                XCTAssertEqual(["name"], columnNames)
+            default:
+                XCTFail("Expected CSVParseError.duplicateColumns")
+            }
+        }
+    }
+    
+    func testNoDuplicateColumnNames() throws {
+        let csvString = """
+        id,name,age
+        1,John,23
+        2,Jane,25
+        """
+        
+        let csvError = try CSV<Named>(string: csvString)
+        let csvRandom = try CSV<Named>(string: csvString)
+        
+        XCTAssertEqual(csvError.header, ["id", "name", "age"])
+        XCTAssertEqual(csvRandom.header, ["id", "name", "age"])
+        
+        XCTAssertEqual(csvError.rows.count, 2)
+        XCTAssertEqual(csvRandom.rows.count, 2)
+        
+        XCTAssertEqual(csvError.rows[0]["id"], "1")
+        XCTAssertEqual(csvError.rows[0]["name"], "John")
+        XCTAssertEqual(csvError.rows[0]["age"], "23")
+        
+        XCTAssertEqual(csvRandom.rows[0]["id"], "1")
+        XCTAssertEqual(csvRandom.rows[0]["name"], "John")
+        XCTAssertEqual(csvRandom.rows[0]["age"], "23")
+        
+        XCTAssertEqual(csvError.rows[1]["id"], "2")
+        XCTAssertEqual(csvError.rows[1]["name"], "Jane")
+        XCTAssertEqual(csvError.rows[1]["age"], "25")
+        
+        XCTAssertEqual(csvRandom.rows[1]["id"], "2")
+        XCTAssertEqual(csvRandom.rows[1]["name"], "Jane")
+        XCTAssertEqual(csvRandom.rows[1]["age"], "25")
+    }
+    
+}