Any bug on opening legendary mercs you can craft?

I opened 70 packs. I only was missing Drek’Thar and Balinda. I have enough coins to craft Balinda.

I opened a legendary portrait (of a merc I already own), then Drek’Thar, then 2 other legendary portraits. All I want is Balinda (so I can save Balinda’s 500 coins).

Is there any bug or rule that lowers or eliminates odds of a legendary that you can already craft? Or did I just get really unlucky? Are the odds of legendary portraits really that high? I get tempted into thinking the new legendary has to be a new merc, and then I get demoralized.

Mercenary Packs only have the guaranteed Legendary Mercenary Card within the first 10 packs.

Then after that it is an average (not guarantee) of one Legendary Mercenary Card every 20 Mercenary Pack.

There is also no guarantee (“pity timer”) for Epic Mercenary Cards.

See Hearthstone Shop (Select Mercenaries Packs tab)

I kind of gave up on opening legendaries on merc packs as it takes way too many packs to even find one the 1x20, 1x40 seems farfetched. Even epics are hard to find when you are looking for epic you get a portrait instead and looking 4 the next epic might take more that you thought it will. So best to save packs and open them only when new mercs are introduce as real rates for lego and epics are really high. I usually wait to have enough coins for lego to craft them. I’m missing 3 or 4 if we count that we got a portrait instead of a merc in last merc patch.

I’ve seen odd behavior but it might very well be luck. for example not opening a legendary I was looking for until after I beat the last available storyline quest and then opening it the 1st pack after.

but I’ve also had some very poor luck including 2 legendaries in something like 89 packs.

apparently there’s an add-on that will track pack opening and should probably grab it before the next round of mercs is released.