I am seeing multiple items in My Workbench when I only have 1 node and a translated version of that node.
I installed a plain Lightning site (lightning-8.x-3.103) I disabled the 3 core moderation modules that are enabled by default now in Lightning: Content Moderation, Workflows, Lightning Workflow, and Scheduler.
I installed what we are using for moderation: Workbench 8.x-1.0, and Workbench moderation 8.x-1.3.
I created 1 node and published it. I went to My Workbench and I see 1 node published.
I enabled all 4 core translation modules: Configuration Translation Content Translation Interface Translation Language
I added the Spanish language. I went to the first node and added a translated version of it. And saved it as a draft.I went to My Workbench and I see 5 items. 4 are the original node and 1 is the translated node. All 5 items link to the original node. If I publish the translated version of the node, then Workbench displays 5 items that are all the translated version and all 5 link to the translated version. See screenshots. One of the Content overview page and the other of the My Workbench page. http://allygem.com/wb-1.jpg