array(
  'filename' => array(
    'name' => 'xxx.png',
    'type' => 'image/png',
    'size' => 2548863,
    'tmp_name' => '/img/sdsdsd.png',
    'error' => 0
  )
)

//name相同
<form method="post" enctype="multipart/form-data">
  <input type="file" name="wt[]"/>
  <input type="file" name="wt[]"/>
  <input type="submit" value="提交"/>
</form>

//name不同（简单点）
<form method="post" enctype="multipart/form-data">
  <input type="file" name="wt"/>
  <input type="file" name="mmt"/>
  <input type="submit" value="提交"/>
</form>

//name相同
array (size=1)
 'wt' => 
  array (size=5)
   'name' => 
    array (size=2)
     0 => string '新建文本文档 (2).txt' (length=26)
     1 => string '新建文本文档.txt' (length=22)
   'type' => 
    array (size=2)
     0 => string 'text/plain' (length=10)
     1 => string 'text/plain' (length=10)
   'tmp_name' => 
    array (size=2)
     0 => string 'C:\Windows\php1D64.tmp' (length=22)
     1 => string 'C:\Windows\php1D65.tmp' (length=22)
   'error' => 
    array (size=2)
     0 => int 0
     1 => int 0
   'size' => 
    array (size=2)
     0 => int 0
     1 => int 1820

//name不同（简单点）
array (size=2)
 'wt' => 
  array (size=5)
   'name' => string '新建文本文档 (2).txt' (length=26)
   'type' => string 'text/plain' (length=10)
   'tmp_name' => string 'C:\Windows\php39C7.tmp' (length=22)
   'error' => int 0
   'size' => int 0
 'mmt' => 
  array (size=5)
   'name' => string '新建文本文档.txt' (length=22)
   'type' => string 'text/plain' (length=10)
   'tmp_name' => string 'C:\Windows\php39D8.tmp' (length=22)
   'error' => int 0
   'size' => int 1820