DuplicateEntityException when running osuser2atluser.jsp migration

When performing the LDAP integration migration, users may run into this error:

com.atlassian.user.impl.DuplicateEntityException: User [admin] already exists in credentialsProvider [bucket.user.providers.CachingCredentialsProvider@21e5f0]
at com.atlassian.user.impl.osuser.OSUUserManager.createUser(OSUUserManager.java:94)
at com.atlassian.user.impl.delegation.DelegatingListUserManager.createUser(DelegatingListUserManager.java:104)
at com.atlassian.user.util.migration.OSUEntityMigrator.migrateUsers(OSUEntityMigrator.java:101)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.springframework.aop.framework.AopProxyUtils.invokeJoinpointUsingReflection(AopProxyUtils.java:61)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:149)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:116)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:56)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:138)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:152)
at $Proxy33.migrateUsers(Unknown Source)
at admin._osuser2atluserjsp._jspService(_osuser2atluser_jsp.java:71)
at com.caucho.jsp.JavaPage.service(JavaPage.java:75)
at com.caucho.jsp.Page.subservice(Page.java:506)