The botXXXXX XXXXXne is that these are essentially the same medications: both have budesonide, which is a steroid medication that reduces inflammation in the airways, and formoterol, which relaxes the airways to make it easier to breathe.
The 200/6 dosing just has twice as much steroid than the 100/6 dose, but it is the same medication.
Here is the quoted information about COPD an Symbicort 200/6:
"In two 12-month studies, the effects on lung function and the rate of exacerbation (defined as courses of oral steroids and/or course of antibiotics and/or hospitalisations) in patients with severe COPD was evaluated. Median FEV1 at inclusion in the trials was 36% of predicted normal. The mean number of exacerbations per year (as defined above) was significantly reduced with Symbicort as compared with treatment with formoterol alone or placebo (mean rate 1.4 compared with 1.8-1.9 in the placebo/formoterol group). The mean number of days on oral corticosteroids/patient during the 12 months was slightly reduced in the Symbicort group (7-8 days/patient/year compared with 11-12 and 9-12 days in the placebo and formoterol groups, respectively). For changes in lung-function parameters, such as FEV1, Symbicort was not superior to treatment with formoterol alone."
Essentially what this is saying is that the steroid part of the medication made a difference in the number of COPD exacerbations, more so than the formoterol alone. The steroid part of the medication was not shown to change the course of the disease though (as evidenced by the lung-function FEV1, the last sentence).
So essentially, by receiving the other medication (the one with 50% of the intended steroid dose) may have made you more susceptible to COPD exacerbations (compared to a full 100% dose) but has no effect on the disease progression itself. In other words, your COPD should not have been affected by the differences in medication. Remember you were taking the same ingredients; just not as much.