The most common methods of photon generation is SPDC and SFWM. I am seeking for a different way of manipulating the pump but still use SPDC in PPLN waveguide to achieve bright photon pairs that might not have been implemented before. Any suggestion on this?

If the sources are different, they add incoherently, i.e. they don't interfere, so the photons are distinguishable by the source label. 

Thank you for your responses. I there then a possible way of removing the incoherency and still generate indistinguishable photons. Is there some work that has been done to this effect? 

Thé sources must interfere. That's what expresses the fact that the photons are indistinguishable.

One has uncertainty relation time-energy. From this relation one can derive uncertainty relation between photon phase and number of photon. So for single photon phase is completely uncertain. If your single photon sources are independent, it makes impossible to produce interference. To produce interference between single photons from different sources your sources have to be quantum correlated. In this case phase of each photon is completely uncertain, but phase difference could be fixed.

Thank you all for your responses. They are very helpful

Please refer the no cloning theorem for further insight.

The no-cloning theorem isn't relevant here: two interfering sources, that produce multiphoton states, by construction, don't allow the distinction of which photon comes from which source. This doesn't mean that the photon states are cloned.  

Thank you all