Attribute "generic.attackDamage" dual wielding

• Item

  /give @p diamond_axe 1 0 {AttributeModifiers:[{AttributeName:generic.attackDamage,Amount:1000000,Name:Bug,Operation:0,UUIDLeast:1,UUIDMost:1}]}

  in offhand slot

• spawn a Horse / Ender Dragon / Wither
• hit it with main hand item

It dies instantly! This shouldn't happen.