When we have duplicate hardware models, either created by auto discoveries or manually on the system, we can merge these hardware models into a single "Master" model.
This will enable us to merge any older hardware model into the new one. When this action has been applied, the hardware model details such as size/type/vendor will be used from the master. There is also an option to add that manual model as an alias to the master.
You can access the merge option by navigating to
Datacenter > Hardware Models.
Select all models that you would like to merge and from the drop-down action menu use "Merge selected hardware models" option:
Then select the master hardware model and the alias option if you need to add all other models as an alias to the master one:
The only requirement for the merge is that the models share the same size, for example you can not merge a 2U model into a 1U model.
If the manual devices were not assigned a size you can adjust them in bulk by navigating to Tools > Templates & Bulk Operations > Bulk Hardware Edit