If you also entered your T5008 information in the Capital Gains Profile, you will have double entries.
You can choose to enter these slips either way, on the T5008 slip page or in the Investment section. The Capital Gains or Losses from either entry methods will transfer to Schedule 3 of the tax return.
If you enter your T5008 slips (or use the CRA AutoFill feature to import) on the T-Slips page in TurboTax, do not enter them again under your Capital Gains & Capital Gains Deduction Profile, and vice-versa. Doing so will cause double reporting.