I "think" lucene.net search index uses file locking so it should be ok with 2 servers both trying to write to the index. However, it would be best if only one of the nodes processes the indexing queue or there could be contention or duplication of search index items as each node tries to process the same rows from the indexing queue table.
There is an undocumented config setting that can be used to turn off processing the indexing queue on all but one node. You could add this to the user.config on all but one of the nodes
<add key="IsSearchIndexingNode " value="false" />
All the nodes can write to the indexing queue so whichever node updates content will queue the content for indexing, but only 1 node should process that queue and write to the search index itself.
Other than that, you tell me what issues you encounter, if any.