Inventory Hopper with filter does not insert different items

[pk-of-tm]

I am trying to use the Basic Inventory Hopper to insert two (or more) items into a Strainer (playing Seopolis Beyond).
The Inventory Hopper is pointing at an Inventory Proxy which is pointing into the Strainer. Then I configured an Item Filter with two Items set to Allow matching and put it into the Inventory Hopper. I would expect that both Items got inserted into the Strainer, but only one of the two gets inserted.
In case you don't know, the Strainer is a machine with 3 inventory slots, one for an Upgrade, one for a Mesh and one for the Block to gather the ressource. I did some tests and when I have configured only one item in the filter it is inserted into the machine. It doesn't matter if it is the Mesh or the Block. So there is no issue with the side i am inserting from, which some machines have.
Is this a bug or a feature? ;-)

Where is the point to be able to add a filter if it gets ignored?
I did test it the other way, Inventory Hopper used as 'Extractor' from a chest. This works just fine.

[Arkdirfe]

I have the very same problem with basins from Create. The problem also occurs for vanilla inventories, it seems to go slot-by-slot through the source inventory, stopping if it can't insert the item instead of checking if other items meet the filter criterion. This seems like an optimization put in place for the normal single-item mode of operation, but completely breaks multi-item filtering.