Perhaps you're thinking of:
* "Titanic sister": This is a term used in maritime history to refer to the RMS Olympic, the sister ship of the RMS Titanic. Both ships were built by the same company and shared a similar design.
* "Titanic survivors": This refers to the people who survived the sinking of the Titanic.
If you can provide more context about where you encountered this phrase, I might be able to give you a more accurate answer.