diff --git a/server/e2e/api/specs/library.e2e-spec.ts b/server/e2e/api/specs/library.e2e-spec.ts
index 0ce192e479e4d..e704cb79e8ff0 100644
--- a/server/e2e/api/specs/library.e2e-spec.ts
+++ b/server/e2e/api/specs/library.e2e-spec.ts
@@ -98,6 +98,36 @@ describe(`${LibraryController.name} (e2e)`, () => {
       );
     });
 
+    it('should not create an external library with duplicate import paths', async () => {
+      const { status, body } = await request(server)
+        .post('/library')
+        .set('Authorization', `Bearer ${admin.accessToken}`)
+        .send({
+          type: LibraryType.EXTERNAL,
+          name: 'My Awesome Library',
+          importPaths: ['/path', '/path'],
+          exclusionPatterns: ['**/Raw/**'],
+        });
+
+      expect(status).toBe(400);
+      expect(body).toEqual(errorStub.badRequest(["All importPaths's elements must be unique"]));
+    });
+
+    it('should not create an external library with duplicate exclusion patterns', async () => {
+      const { status, body } = await request(server)
+        .post('/library')
+        .set('Authorization', `Bearer ${admin.accessToken}`)
+        .send({
+          type: LibraryType.EXTERNAL,
+          name: 'My Awesome Library',
+          importPaths: ['/path/to/import'],
+          exclusionPatterns: ['**/Raw/**', '**/Raw/**'],
+        });
+
+      expect(status).toBe(400);
+      expect(body).toEqual(errorStub.badRequest(["All exclusionPatterns's elements must be unique"]));
+    });
+
     it('should create an upload library with defaults', async () => {
       const { status, body } = await request(server)
         .post('/library')
@@ -229,7 +259,7 @@ describe(`${LibraryController.name} (e2e)`, () => {
         );
       });
 
-      it('should not allow an empty import path', async () => {
+      it('should reject an empty import path', async () => {
         const { status, body } = await request(server)
           .put(`/library/${library.id}`)
           .set('Authorization', `Bearer ${admin.accessToken}`)
@@ -239,6 +269,16 @@ describe(`${LibraryController.name} (e2e)`, () => {
         expect(body).toEqual(errorStub.badRequest(['each value in importPaths should not be empty']));
       });
 
+      it('should reject duplicate import paths', async () => {
+        const { status, body } = await request(server)
+          .put(`/library/${library.id}`)
+          .set('Authorization', `Bearer ${admin.accessToken}`)
+          .send({ importPaths: ['/path', '/path'] });
+
+        expect(status).toBe(400);
+        expect(body).toEqual(errorStub.badRequest(["All importPaths's elements must be unique"]));
+      });
+
       it('should change the exclusion pattern', async () => {
         const { status, body } = await request(server)
           .put(`/library/${library.id}`)
@@ -253,7 +293,17 @@ describe(`${LibraryController.name} (e2e)`, () => {
         );
       });
 
-      it('should not allow an empty exclusion pattern', async () => {
+      it('should reject duplicate exclusion patterns', async () => {
+        const { status, body } = await request(server)
+          .put(`/library/${library.id}`)
+          .set('Authorization', `Bearer ${admin.accessToken}`)
+          .send({ exclusionPatterns: ['**/*.jpg', '**/*.jpg'] });
+
+        expect(status).toBe(400);
+        expect(body).toEqual(errorStub.badRequest(["All exclusionPatterns's elements must be unique"]));
+      });
+
+      it('should reject an empty exclusion pattern', async () => {
         const { status, body } = await request(server)
           .put(`/library/${library.id}`)
           .set('Authorization', `Bearer ${admin.accessToken}`)
diff --git a/server/src/domain/library/library.dto.ts b/server/src/domain/library/library.dto.ts
index e12ca4c185d2d..638841ec63800 100644
--- a/server/src/domain/library/library.dto.ts
+++ b/server/src/domain/library/library.dto.ts
@@ -1,6 +1,6 @@
 import { LibraryEntity, LibraryType } from '@app/infra/entities';
 import { ApiProperty } from '@nestjs/swagger';
-import { IsBoolean, IsEnum, IsNotEmpty, IsOptional, IsString } from 'class-validator';
+import { ArrayUnique, IsBoolean, IsEnum, IsNotEmpty, IsOptional, IsString } from 'class-validator';
 import { ValidateUUID } from '../domain.util';
 
 export class CreateLibraryDto {
@@ -20,11 +20,13 @@ export class CreateLibraryDto {
   @IsOptional()
   @IsString({ each: true })
   @IsNotEmpty({ each: true })
+  @ArrayUnique()
   importPaths?: string[];
 
   @IsOptional()
   @IsString({ each: true })
   @IsNotEmpty({ each: true })
+  @ArrayUnique()
   exclusionPatterns?: string[];
 
   @IsOptional()
@@ -45,11 +47,13 @@ export class UpdateLibraryDto {
   @IsOptional()
   @IsString({ each: true })
   @IsNotEmpty({ each: true })
+  @ArrayUnique()
   importPaths?: string[];
 
   @IsOptional()
   @IsNotEmpty({ each: true })
   @IsString({ each: true })
+  @ArrayUnique()
   exclusionPatterns?: string[];
 }