STM32 F4 – ADC in Dual Mode Simultaneously

I am stuying the example from STM32 libraries (ADC_DualModeRegulSimu). I understand how the whole program works but I need some information and I have few questions about this code confronting to my project.

First of all, I need to convert 2 analog values simultaneously because I plan to compute a phase correlation (that's why I need the simultaneously conversion).
In the code, the converted value are put in a word of length 32 bits :
extern __IO uint16_t aADCDualConvertedValue[2];

I want to stock the first and second value (half-word) in two vector that I have defined. I first decided to create a while statement like this :

while(counter < Max && ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC && ADC_GetFlagStatus(ADC2, ADC_FLAG_EOC)) {
    vector1[counter] = aADCDualConvertedValue[0];
    vector2[counter] = aADCDualConvertedValue[1];
    counter++;
}

But, this method seems to be unsafe because, we can't be certain that aADCDualConvertedValue[0] and aADCDualConvertedValue[1] are sampled at the same time owing to the number of cycles taken by while conditions.
So, what's the best way to stock the simultaneously data safely ?

Another problem, the conversion starts like this (after initializing the two ADC) :
ADC_SoftwareStartConv(ADC1);
ADC_SoftwareStartConv(ADC2);

Does-it mean that ADC2 starts to convert one cycle after ADC1, thus first both samples are not converted simultaneously ?

Thks.