Google - English language question. See details?

Yes you do.

Let's split the sentences to 2 parts.

1) 'If A is accompanied by B and C you must carry out Z.'
This means that if you have A with both B and C (all 3 together), you carry out Z.

2) 'If A is accompanied by B or C you must carry out Z.'
Here there are 2 sub-parts:
a) 'If A is accompanied by B you must carry out Z.'
This means that if you have A and B you should do Z. (This is the answer to
your questions.)
"or" b) 'If A is accompanied by C you must carry out Z.' So if you have A and C you
do Z.

I hope this was helpful.