What is one Subcontractor for two projects?

I am working in Construction and I don't see any harm going to the same contractor for 2 running projects. It will have a great advantage as it will have a smooth running of the project and you will have a greater leverage in dealing with the terms of payment with the same contractor.

You go with the same sub contractor provided they have satisfactory done previous jobs with your organization; solid financial backing; reliable technical skills & manpower and especially expertise or experience on the works you want to award to them 

As I understand the question is : can we take one sub-contractor for two running projects? In principle, there is no harm or bar in taking the same sub-contractor for two projects provided:

• The sub-contractor has sufficient Financial, HR, Technical, Administrative resources for both projects.
• There is no conflict of interest in the two projects. 

In some big projects, it may happen that for smooth execution works, the main contractor(s) subcontract some ancillary or odd works to another contractor at his own risk and responsibility but with the approval of the contracting authority. May be in country specific condition, the subcontractors have a bit different meaning.

  If it is the main contractor with two projects and without adequate capacity, technical skills and financial capacity, there would be severe problem for the contractor to make progress as planned and he may even fail.  

But contractor with huge financial power and technical skills (like Korean contractor) will carry out the works successfully. 

I experienced that situation once, if you consider the capability of the contractor for each project separately, you are going to put your project on a huge "double" risk. delays and a lot of rejected work, conflicts and trade-offs.

As per my experience. There will be no problem to award multiple Projects to one Sub Contractor.

Let me add my previous experience fro Freight Forwarding terms. we were awarding our Import FOB volume to one vendor. who is handing and giving us value added services along ample credit period. He was Handling more than 100 TEUS per month import cargo. to support him we also instruct our supplier to give him volume share by our CFR nomination biz. as per my view we handled it smoothly and he is the one who cater our requirements at that time.