Date filters - last week vs last month - different behaviour - bug?

I have a list of records with dates. I have a table view displaying those records. I have added a filter menu:

Link name  | Field |                         | Value

This week  | Date | is during the current   | week

Last week  | Date | is during the previous | 1 weeks

This month | Date | is during the current   | month

Last month | Date | is during the previous | 1 months

"This week" and "this month" filter options work as expected.

"Last month" seems to show just last month, excluding the current month (e.g. it is now April. Filtering using the "Last month" option results in just March records).

But "Last week" seems to show last week and this week (e.g. it is now 17 April. Filtering using "Last week" results in records from 6 April to 17 April).

Ideally I want "Last week" to work as for "Last month" i.e. exclude the current week.