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Not for a planet, but for a smaller body.

Massive bodies are in hydrostatic equilibrium. Gravity pulls them into spheres, eliminating most non-negligible variations from perfect roundness. Obviously, protrusions like mountains exist, but they're minute compared to the size of a planet.

That said, smaller bodies may not be in hydrostatic equilibrium, and this sort of object can form. 67P/Churyumov"“Gerasimenko, for example, is a comet that has a barbell-shaped nucleus. You could absolutely get a minor body shaped like this.

^{Image from the ESA, under the Creative Commons Attribution-ShareAlike 3.0 IGO License.}