Ah, I think I see where you're leading with last bar's close. In a (very unlikely) situation when there was no trading at all in a 1 minute period, yes, if you want that slot filled you could copy the close price from the last bar to all of OHLC of the current bar. It's the best approximation.

Of course, situations like that should be very rare in todays forex market. But as it is fragmented (not centralized) some less popular brokers could see periods of inactivity. Although 1 minute is a long long time...