Tons of different way

Scheme 1:
Use HPWM to produce your 0-5 volt
Use a op-amp and use the Vref signal to produce you 2nd 0-2.5 volt. If you can deal with the resolution.. it works.

Scheme2:
Use HPWM for your 0-5 volt
Create a timer based PWM to create the second PWM channel

Scheme3:
Use 2 DAC. MAX437 is simple and cheap

Scheme4:
Use Darrel Taylor Multi SSPWM. So you may produce few different voltage output.

Scheme5:
Create you own multi PWM output based on Timer interrupts.

Scheme6:
Use a PIC with 2 CCP module.. hence two PWM output. 16F876,16F877 and the list is long enough to fill the screen here

Scheme7:
Use 2 PIC with 1 PWM. 1XPIC16F628 + PIC 12F683 talking together.

There's some others but it should be enough to start?