Although loads of questions posted here, mine is a little different- at least i think so.

Situation

Have been working with a Thai company, all legal etc, with a WP for 6 years. In July, the company was going through a bad patch, so I found myself another job. Last month I went to HK to get a three month Non Imm B visa using the documents of the new employer.

after working for the previous 6 years I decided to take a month to unwind etc and had planned to use the Non Imm B to get a WP early next month.

In the meantime, the old original company has bounced back and now want me to rejoin them

Obviously to return to the fold, so to speak, I will be using the original companies docs to process the WP BUT is it possible to do this. In other words is it acceptable to use one companies docs for the Non Imm B visa and then apply for the WP with a second companies documentation.

For the record the "new company" although disappointed have no objections

Visas are from Immigration, Work Permits from the Labour dept.

Different organisations, so I do not beleive you will have a problem,

but no doubt others will comment.

No problem.

In other words is it acceptable to use one companies docs for the Non Imm B visa and then apply for the WP with a second companies documentation.

Yes, as already stated, this will definitely not be a problem - no cross checks are made plus there is no written reference to the 'visa sponsoring company' on your actual visa.