These are two of my favorite names and I think they work really well together as twins. Similar in style, but not too matchy and have different initials (I don't mind same initials but some people don't like it).
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LISTEN TO THE MUSTN'TS
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Shel Silverstein
Listen to the MUSTN'TS, child,
Listen to the DON'TS
Listen to the SHOULDN'TS
The IMPOSSIBLES, the WON'TS
Listen to the NEVER HAVES
Then listen close to me—
Anything can happen, child,
ANYTHING can be.