nina24 - I had a similar situation - initially applied for a work permit for a certain job...but by the time it was issued, the job was gone. As I had the legal status to work, I just found another position at another company without reapplying to change my work permit. To tell you the truth I only applied for a change in the employer's name after a year of working at the job.
In my work permit application to change employers....I explained how employer wanted me to start right away and how my job was gone....and they changed my work permit without hassles...
So, when I applied for CEC, I only included my current work permit - i.e with my current employer...So that's all Buffalo checks for - that you have legal status in Canada and that you obtained your work experience under a work permit - I guess they don't really have tthe time or resources to check all your history (student permits, work permits...) with Vegreville.
This is for the very same reason that for e.g when you call the CIC hotline, they cannot really see much on Buffalo applications - they are designed mostly to deal with applications within Canada.
In your case, if you do qualify for the open work permit, I would suggest to change to it.....this way when you apply for CEC you may not even have to mention about the second job....as all you need is 1 or 2 year of job experience in the proper NOC.
After all, I am sure this was a very common problem with employers not willing to wait for the work permit...and being hesitant to give you a letter of employment.....when they found out you needed to apply for a work permit in order to work....partially why CIC changed to an open work permit policy....