The shoring and excavation activities shown in these two photos are clearly for the Liberty Central site - they are abutting the existing building to the west. Shoring piles are in process - the top stub of one of the completed piles is visible under the Caution sign. The entire site, including the 39 East Liberty area, has been cleared though, and looks ready for construction - so it may indeed be both buildings at once.
A side note on what used to be here - for many years the building on this lot housed the head office and data centre for Inglis Canada. Behind (to the west) of the head office building was the Inglis washing machine factory. The factory even included a foundry where metal ingots were melted down and cast into impellers for the washing machines - looked like it was straight out of a Victorian England Dickens type factory. Of course, all long, long gone now.
Even before any of these surrounding condos started construction, this area was terrible for traffic. I can't imagine how bad traffic will become once the area is all build up, it's gonna be CRAZY!