What's the difference between 慢走mànzǒu and 慢慢走mànman zǒu?

A: 我要回去了。再见。Wǒ yào huíqù le. Zàijiàn!
B:慢走。Mànzǒu.

A: 妈妈,我摔倒了. Māma, wǒ shuāi dǎo le.
B: 我说过你应该慢慢走。Wǒ shuō guo nǐ yìnggāi mànman zǒu.

Can you find out the difference between 慢走mànzǒu and 慢慢走mànman zǒu?