fix: Only add the level ID when it has not been looked at before

src/pages/level.tsx

@@ -54,13 +54,13 @@ export default class LevelPage extends React.Component<IProps, IState> {
         // Check if the vocab was already looked at
         const lookedAt = this.state.lookedAt.find((el) => el === vocab.id) || vocab.id === 0;
 
-        // TODO: Actually update the "Vocab View" when clicking
         return <ListItem button key={this.genUID(vocab)} onClick={() => {
             // Prevent the user from using too much memory by always clicking on the elements
             // Show the clicked at vocab word
+
             this.setState({
                 currentVocab: vocab,
-                lookedAt: this.state.lookedAt.concat(vocab.id),
+                lookedAt: lookedAt ? this.state.lookedAt : this.state.lookedAt.concat(vocab.id),
             });
         }}>
             <ListItemText>