They share the front sides total mana cost, and when not on the battlefield, they only have the characteristics of the front side
Pokemon will claim to combat scalping and Costco brawls yet completely incentivize them with distribution, limited drops, and nerfed pull rates
I will say this about Mangara, the Diplomat though: if you draw just 1 card on average per turn, then it's worth playing in Mono White decks
Meanwhile Red has access to a lot of targeted artifact hate - Manic Vandal, Ingot Chewer, and Oxidda Scrapmelter - and White has primarily access to the enchantment hate - Dawnbringer Cleric, War Priest of Thune, Wispmare
They might not be a meaningfully supported archetype in most sets, but you still find them, often as a boon for doing something simple like triggering heroic on Phalanx Leader, to juicing up a card like Ancient Animus, or just to make an aggressive deck more viable
Teeth bigger