How does 'discarding your lowest/highest' work?

Greetings!

I love warlock. Some of my favorite effects involve discarding other cards. There are various types of discarding cards but I want to ask about Expired Merchant.

( I am making a huge assumption that Shriek or Reckless Diretroll basically work the same way except for targeting the highest card in hand, Shriek and Reckless Diretroll target the lowest.)

Here is my Scenario: 

I have Expired Merchant in hand along with Cruel Dinomancer and Reno Jackson. Assuming no other card is greater than 5 mana in hand which card will be chosen? Is this random? Is the card that is Alphabetical first/last? Does it target the cards from left to right or right to left. Does it choose the card based on which card set came first? Is there any rhyme or reason once two cards are of the same mana level in hand? Do I have to play Reno to order to guarantee that Cruel Dinomancer is selected?

Is this mechanical process the same when dealing with discarding your lowest and highest cost cards?

Thank you for your time!

It's hearthstone... So it's random

Although not 100% sure, my guess is: If you draw Reno first, followed by Dinomancer, Reno might be discarded. Reason is: Game registers the "firsts", similar to this scenario: You have Piloted Shredder and Piloted Sky Golem on-board. Shredder is played first, then Sky Golem, and wherever you put your minions is irrelevant in any matter. Mage played Flamestrike and your Mechs will start to pop-up: First Shredder, then Sky Golem. Unless an exclusive rule that I have never heard of states otherwise, discarding your lowest-highest card should work the way I have illustrated.

This question has already been awsered many times by famous streamers, pro players and websites like reddit.

In case of tye in numerical values (higher cost minion), the chosen option will always be random. As long as you have both in hand, you have a 50/50 chance to discar either reno or dinomancer.

hope this helps.

Quote From Esparanta

Although not 100% sure, my guess is: If you draw Reno first, followed by Dinomancer, Reno might be discarded. Reason is: Game registers the "firsts", similar to this scenario: You have Piloted Shredder and Piloted Sky Golem on-board. Shredder is played first, then Sky Golem, and wherever you put your minions is irrelevant in any matter. Mage played Flamestrike and your Mechs will start to pop-up: First Shredder, then Sky Golem. Unless an exclusive rule that I have never heard of states otherwise, discarding your lowest-highest card should work the way I have illustrated.

Deathrattles do occurr in the order they were played if killed at the same time, but discard mechanics associated with lowest or highest cost dont consider when you draw the card, it choses at random.