can i use a single voltage regulator to power two usb ports
Use of common power supply for ALL USB ports in a host/hub design is very common practice. This type of power distribution is called "ganged" power, and is used in vast majority of PC desktop mainboards. The USB ports don't have to have power protection or current limiting, the limiting and corresponding overcurrent reporting is optional. USB specs says (Section 7.2.1 of USB 2.0 base specification) that ports MUST SUPPLY AT LEAST five units of load (one unit = 100 mA for USB2, and 150 mA for USB3), which means no upper limit. However, to avoid potential overloading of connectors and internal system components it is wise to limit the current at the source, using either high-side power switches or simple resettable polyfuses.

One thing, however, is a must: the power distribution network between ports must be decoupled to a certain degree. The reason is to protect already connected and working port from power glitches related to hot-plug of another USB device. This effect is called "droop" in USB terminology. USB specification mandate that the droop on an already functional port shouldn't be more than 330 mV when a standard load of 10 uF ( in || 44 OHms) is connected to an adjacent USB port. It is called "droop test". The proper de-coupling is usually achieved with trace separation, placing ferrite beads, and individual port bypass caps (47 - 100 uF) close to each port VBUS pin. 

For recommendations of component placing and board routing, look up reference designs of USB hubs, say, on MICROCHIP.COM