Although the SGC has been using the Beta Stargate discovered in Antarctica since Small Victories (2000), the point of origin of the Alpha Stargate is clearly visible as opposed to the point of origin of the Beta Stargate that was previously seen in Solitudes (1998).
When the two SG teams are preparing to enter the Stargate to visit the Tok'ra, the reflection of the event horizon on the window of the Stargate Operations room does not resemble a normal event horizon.