我想分析六个二分类变量的潜在类别。命令如下，为什么出现如下的错误呢？duplicates。。。是什么意思？

TITLE: LCA with  binary latent
       class indicators
DATA:        FILE IS mplus.dat;

VARIABLE:        NAMES ARE core
           close fcontact tcontact
           attsup rinc ginc rins
           gins;

USEVARIABLES = core close fcontact
               tcontact attsup rinc
               ginc rins gins;

CLASSES = c (4);

CATEGORICAL = core close fcontact
              tcontact attsup rinc
               ginc rins gins;

ANALYSIS:        TYPE = MIXTURE;  

OUTPUT:        TECH1 TECH8 TECH10;




结果命令如下：报错了

TITLE: LCA with  binary latent
         class indicators
  DATA:        FILE IS mplus.dat;

  VARIABLE:        NAMES ARE core
             close fcontact tcontact
             attsup rinc ginc rins
             gins;

  USEVARIABLES = core close fcontact
                 tcontact attsup rinc
                 ginc rins gins;

  CLASSES = c (4);

  CATEGORICAL = core close fcontact
                tcontact attsup rinc
                 ginc rins gins;

  ANALYSIS:        TYPE = MIXTURE;

  OUTPUT:        TECH1 TECH8 TECH10;

*** ERROR in VARIABLE command
  Duplicate variable on NAMES list:  CORE
*** ERROR in VARIABLE command
  Duplicate variable on NAMES list:  CLOSE
*** ERROR in VARIABLE command
  Duplicate variable on NAMES list:  FCONTACT
*** ERROR in VARIABLE command
  Duplicate variable on NAMES list:  TCONTACT
*** ERROR in VARIABLE command
  Duplicate variable on NAMES list:  ATTSUP
*** ERROR in VARIABLE command
  Duplicate variable on NAMES list:  RINC
*** ERROR in VARIABLE command
  Duplicate variable on NAMES list:  GINC
*** ERROR in VARIABLE command
  Duplicate variable on NAMES list:  RINS
*** ERROR in VARIABLE command
  Duplicate variable on NAMES list:  GINS
*** ERROR in ANALYSIS command
  TYPE=MIXTURE is not available for multiple group analysis.


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