What are these two "Dialup Device"s that suddenly appeared on my Macbook Pro?
Most probably they appeared if you have ever connected to some other devices (other mobile phones, for instance) which shared their internet connection with you OR for charging.

Another possible reason is that someone near you has a device with the ability to create a personal Wi-Fi hotspot. Your computer is able to detect this so will add it to your list of available providers.

You can safely delete them. No, this is not dangerous and doesn't look like an attempt for hacking.

Also, check this for security: Prevent my Mac from connecting to an unsecure Wi-Fi network?