Freezing and thawing cannabis seeds repeatedly will significantly lower their viability rates. Each time you bring your seeds out of the freezer, moisture from inside condensates through the shell of the seed and evaporates. When this is repeated multiple times the process will eventually dry out and kill your seeds.
Another issue is mould. Every time your seeds become wet on the outside from thawing condensation you will greatly increase the risk of mould if and when you do decide to germinate. We do not advise freezing seeds to preserve them especially if you plan to remove them and re-store them several times.
Even if you do not thaw your seeds from frozen storage it is not advisable to remove seeds from the frozen environment, open the container of seeds to remove a number of seeds and then refreeze the rest immediately. Simply by opening the container you will allow new moisture filled air into it and this moisture can subsequently damage your seeds by causing mould problems.