Changed the code so the returned signal measured in a function. (easier to view)
Attached code for whoever wants to use and modify.
For reading 2 or more ultrasonic sensors, you may want to try using the NewPing library as it supports timer interrupts for an event-driving programming style. While NewPing doesn't ping two sensors at the same time, it allows you to ping sensors very quickly (less than 30ms apart), which should almost always give the same result. As a bonus, your sketch can be doing something else while it is in the ping process as it uses a timer interrupt while waiting for the ping echo.
Using NewPing, one user has 15 sensors connected to a single project and with the event-driven method there's time to process this information. Below is a link to the NewPing library as well as the 15 sensor example sketch (which could be easily adjusted to just ping 2 or any number of sensors).NewPing15 Sensor Example Sketch