According to this article it says that the "validator election algorithm will rotate your stake among those validators on a per-era basis, so you may have a different active validator amongst your selected validators for each era, but you cannot choose which specific validator you will be actively nominating in a given era unless you are nominating just one validator" (the 'active' validator).
It says that "unless you are staking with a considerable amount, you will be nominating a single validator in each era with your full stake". This indicates that it might be possible to nominate more than one validator at a time in each era, such that they'd both be shown as 'active', but only if you were to try nominating with a considerable amount (a considerable amount that is larger than just 1000 5IRE). Otherwise, if 1000 5IRE isn't considered a considerable amount, then you will only be nominating a single validator that would be 'active' in each era with your full stake of 1000 5IRE.
If you nominated both of the validators with an amount that isn't considered a considerable amount then each era you will be actively nominating only a single validator with your full stake, so only one of them would be 'active', whilst the other one would be 'inactive'. Since you didn't nominate only one validator, you nominated both of them, the validator election algorithm will rotate your stake among those validators each era, so you may have a different 'active' validator each era. If you wait until a subsequent era do they rotate such that the 'active' validator becomes 'inactive' (whilst the 'inactive' validator becomes 'active')?
It also says that 'inactive' validators "are in the active validator set and your list of nominations. However, you are not actively nominating them for this era (they are not active for you)". So the reason why one of your validators is 'inactive' in that era is because you are not actively nominating them for that era.