That would definitely account for the difference in potency then, because I would venture to say that they are pretty equal in terms of potency.
I'd recommend straining it to the point where there is a little bit of sediment left in the bottom of the bowl/mug but not to the point where it's gone completely. Then again, it depends on what you GI system can handle. The more sediment, the more potent but you also run the risk of the lingering effects, dermopathy, and GI discomfort.
Next time you try the Melo Melo, try 6tbsp if you plan on double-straining again and it should be about right. I've found that differing sediment amounts can account for 1-3 tbsps depending on how large the difference is. For example, if I toss and wash Nambawan (100% sediment), I only need 2tbsp. If I strain it with only 1 nylon stocking I need 5tbsp. If I strain it with 2 nylon stockings (doubled up) then I need 6tbsps.