Examples:

• The actor's son is a dead ringer for his father, they look almost identical.
• She's a dead ringer for her grandmother when she was young, it's uncanny.
• The suspect in the lineup was a dead ringer for the eyewitness's description.
• The antique watch he found at the flea market is a dead ringer for the one his grandfather used to own.
• The two breeds of dogs are dead ringers for each other, it's hard to tell them apart.
• The actress's costume and makeup made her a dead ringer for the historical figure she was portraying.
• The singer's voice is a dead ringer for the original artist, it's like listening to a recording.
• The counterfeit painting is a dead ringer for the original, fooling even experts.
• The new employee is a dead ringer for the previous one, they could be mistaken for siblings.
• The impersonator's mannerisms and voice made him a dead ringer for the famous celebrity.