"These olives are in Rome."
Translation:Hae olivae Romae sunt.
There are plenty of false positives, but it's not a thing that moderators can fix. It's only at the software level, so, you should rather email Duolingo/fill a bug report or post on the troubleshooting forum. But the moderators already know that they are a lot of problems with wrong answers accepted with the "you had a typo".
They are the same word. However 'hoc' is the singular neuter (being not masculine nor feminine) nomitive and accusitive form, whereas 'hae' is the plural feminine nomitive form.
nota bene, there is also 'hōc'. Without the macron, which duolingo and many other text omit, it looks identical to 'hoc' but it's actually the singular masculine and neuter ablative form.
(Fun fact, you can't edit comments on the mobile app, only delete, so if this comment appears twice, blame the android app)