Layers get identified by the so called layer identifier. The layer identifier can be made out of:

•layer name

•top level group name

•top level group name // layer name

•top level group name // group layer name

 

So if the map document contains multiple group levels in the table of contents, only the top level group layer name is saved in the layer identifier together with the layer or group layer name. Therefore, it is possible to assign identical layer names or group layer names in two differing top level group layers. On the other hand group layers of lower level will NOT be considered in the layer identifier. This is the reason why unique layer names or group layer names are necessary in differing group layers of one top level group. See the screenshot below for details how layer and group layer nomenclature will affect the formation of layer identifiers. On the left the original table of content is displayed, on the right it is possible to see which layers would have to be renamed because of identical layer identifiers.

 

Layer identification in WebOffice 10.9 R4 - Identical layer or group layer names are only possible once per top level group

 

The reason for identifying layers this way (instead of referring to the table of content-position dependent ArcMap layer id) is that you do not have problems when moving layers within your map document.

Whenever the layer identifier changes, WebOffice author updates the changes.