[Telepathic Intruder]

We know Mars once had liquid water, due to its many dried up river beds, which is not possible now.

But does that alone qualify as "earth-like"? At some point Mars lost its magnetic field and the solar wind took away most of its atmosphere, and the water froze or evaporated. That is the most common theory I've heard. It was also hit by a very big asteroid. Maybe it was a combination of the two.

But you have a point which changes mine. Likely this 'second Earth' is similar to Mars, or similar to Venus. Very unlikely that without a magnetic field it's similar to Earth, however. At least not for very long.

[SunkenCiv]

We know that Mars has formations indicating the brief, localized presence of liquid water. Probably these are due to impacts, which melt subsurface ice and produce a temporary microclimate made up of water vapor, making liquid water possible. This best explains the from-nowhere-to-nowhere patterns of all the known channels.