А это что:
{"header": "Foto", "width": "100", "sortable": "false", "dataIndex": "foto","renderer": "this.renderChunk","renderoptions":"[{\"name\":\"tpl\"}]"},
{"header": "Foto", "width": "100", "sortable": "false", "dataIndex": "foto","renderer": "this.renderChunk","renderoptions":"[{\"name\":\"tpl\"}]"},