**No**, it does not mean they have the same HP IVs. If they have the same HP IVs they'll have the same HP (assuming they all have no effort points), but it doesn't go the other way around - many different HP IVs can result in the same HP value.

For example, a level 5 Anorith with no effort points can have 19, 20 or 21 HP, but its HP IV can be anything from 0-31. Thus, you could have one Anorith with 19 HP that has an HP IV of 0 and another Anorith with 19 HP that has an HP IV of 9. At level 5 they're the same, but at level 100 the first Anorith's HP would be nine points lower than the second Anorith's.

If one Anorith's HP is higher than another's (assuming they haven't been in any battles), though, you can be sure that the one with the higher HP has a higher HP IV.

You can calculate your Pokémon's possible IVs from their stats using an online IV calculator such as this one.