size - integrity of list in elasticsearch messed up while paging -

i using version 0.90.0 of elastic-search , stumbled upon strange problem: after filled index documents, using sort , from/size works properly. when overwrite document updating it, messed up.

{   "size": 2,   "from": 0,   "sort": {     "arbitraryfield": {       "order": "asc"     }   },   "query": {     "match_all": {}   } } 

when increase 0 2 , 4, same documents show multiple times. neither sorting on boolean fields nor strings (multi field sortable member) work properly.

same results java-api , elasticsearch-head.

has encountered before and/or solution approaches? many in advance!

edit: @javanna: tried different mappings. boolean fields, used no explicit mapping strings follows:

"document" : {    "properties" : {      "arbitrarystring" : {"type" : "string", "index" : "not_analyzed"}   } 

}

@imotov: yes, _id same. if try match_all query , size documents, there no duplicates. when paging size , from.