Echo Circlet

• WOTC Official Reminder Textofficial rules
  Equip — Equip [cost] ([cost]: Attach to target creature you control. Equip only as a sorcery.)

• WWizards of the Coast2011-01-01
  Official Ruling
  Echo Circlet’s effect is cumulative. If it equips a creature that can already block an additional creature, now it can block three creatures. The same is true if two Echo Circlets equip the same creature, for example.
• WWizards of the Coast2011-01-01
  Official Ruling
  Destroying or unequipping the Echo Circlet after blockers have been declared will not undo any blocks made by the equipped creature.

Rulings via Scryfall