hibernate注释建表的时候总提示重复的外键管理

我的实体集如下
package com.vscut.erp.model;

import javax.persistence.*;
import java.util.Set;

/** 数据字典商品分类

• Created by ShuD on 2016/5/24.
  */
  @Entity
  @Table(name="dictGoodClass")
  public class DictGoodClass extends DataDictBase{
  @Id
  @SequenceGenerator(name = "good_generator", sequenceName = "GOOD_SEQ")
  @GeneratedValue(strategy=GenerationType.SEQUENCE, generator = "good_generator")
  @Column(unique = true, nullable = false, precision = 5, scale = 0)
  private long id;
  private String code;
  private String name;
  @ManyToOne
  private DictUnit unit1;
  @ManyToOne
  private DictUnit unit2;
  private String permissionCode;//许可证代码
  private String normalTax;//普通税率
  private String favTax;//优惠税率
  private String exportTax;//出口税率
  private String consumeTax;//消费税率
  private String addTax;//增值税率
  @OneToMany(cascade=CascadeType.ALL,fetch=FetchType.LAZY,mappedBy="dictGoodClass")
  private Set factors;
  private String remark;
  @Column(nullable = false, length = 255)
  public String getCode() {
  return code;
  }

  public void setCode(String code) {
  this.code = code;
  }
  @Column(nullable = false, length = 20)
  public String getName() {
  return name;
  }

  public void setName(String name) {
  this.name = name;
  }

  public long getId() {
  return id;
  }

  public void setId(long id) {
  this.id = id;
  }

  public DictUnit getUnit1() {
  return unit1;
  }

  public void setUnit1(DictUnit unit1) {
  this.unit1 = unit1;
  }

  public DictUnit getUnit2() {
  return unit2;
  }

  public void setUnit2(DictUnit unit2) {
  this.unit2 = unit2;
  }

  public Set getFactors() {
  return factors;
  }

  public void setFactors(Set factors) {
  this.factors = factors;
  }

  public String getRemark() {
  return remark;
  }

  public void setRemark(String remark) {
  this.remark = remark;
  }

  public String getAddTax() {
  return addTax;
  }

  public void setAddTax(String addTax) {
  this.addTax = addTax;
  }

  public String getConsumeTax() {
  return consumeTax;
  }

  public void setConsumeTax(String consumeTax) {
  this.consumeTax = consumeTax;
  }

  public String getExportTax() {
  return exportTax;
  }

  public void setExportTax(String exportTax) {
  this.exportTax = exportTax;
  }

  public String getFavTax() {
  return favTax;
  }

  public void setFavTax(String favTax) {
  this.favTax = favTax;
  }

  public String getNormalTax() {
  return normalTax;
  }

  public void setNormalTax(String normalTax) {
  this.normalTax = normalTax;
  }

  public String getPermissionCode() {
  return permissionCode;
  }

  public void setPermissionCode(String permissionCode) {
  this.permissionCode = permissionCode;
  }
  }

然后每次程序运行的时候它都会报对于DictUnit对象存在重复的引用约束，我想问这个问题怎么解决....
不好意思直接就贴代码，但是真的怎么百度都百度不到，求大神，谢谢了

@ManyToOne
private DictUnit unit1;
@ManyToOne
private DictUnit unit2;
应该是这里吧。在同一类下，你怎么定义了两个many to one 呢？
改成many to many
private Set< DictUnit> unit;