@midcenturymodernmess Different situation here, as we're a same sex family who used a sperm donor, so single donation in a situation where its obviously we needed a donation.
I think it is worth considering these types of things at this stage of planning, because it is important to know how you want to parent, what you want to share etc etc. My wife (who is not genetically related) has found it really challenging having certain family members (her fathers partner) making comments about where our DD gets certain traits / comments around taking after me, or general nosiness about what we know about the donor. So I think its is worth thinking about how to address these things.
If you're in a situation where its known / suspected you'd need DD by family/friends, and you would like to say something, it might be worth deciding at what point you'd want people to know (during treatment, or if a pregnancy is achieved) and how to address it. It can be as simple as saying something like "we're proceeding with fertility treatment using double donation. We don't want it to be a secret from any future child/ren or our family. However, we would like to ask you to be respectful of our decision not to share details about the donors, and would ask you to try to be considerate of our situation by avoiding statements about who the child will look like / take after etc".
For family / friends you don't want to explain everything to, but feel may ask, you can leave it simple and just say something like "at the moment we'd prefer not to share details about current decisions we've made on our fertility journey".
I think the honest reality is that people only have a set range of standard questions when you're pregnant (do you know what you're having?) and when baby is born (who do you think they look like?). The "who do they look like" is such a evolutionarily driven question, and one I don't think people will mean to ask with any kind of malice. If you are successful, you can work on responses such as "they look like themselves" for example, that just embrace that the baby is their own individual. In my experience, these types of questions really just come in a phase when there isn't much else to say about a newborn, and really reduce once baby is older and they have more personality etc.
The other thing to consider, is that some friends / relatives will discuss who baby looks like / takes after to help reinforce that baby is like you and your partner, which could be quite affirming. My DD displays interests / traits like my wife, and its nice to be able to say "she take after you".
In the future if you are successful, you can make your own personalised book to help tell your child their own unique story: https://www.sensitivematters.net/c/80/the-magic-of-you