Tip 352: Alternate Calendars

Tip 300: Save Time Using Templates
Tip 301: Printing Just One Page
Tip 302: Web Toolbar Search Engine
Tip 303: Outlook 2003 SP2
Tip 304: BCC and Reply-to-all
Tip 305: More Flagging BCC Messages
Tip 306: Run Rules Later
Tip 307: Shortcuts for Next Message
Tip 308: Check Every Minute?
Tip 309: Printing Email
Tip 310: Calendar & Long Months
Tip 311: Store Additional Phone Num.
Tip 312: Can't Print?
Tip 313: Outlook Loads at Startup
Tip 314: Expanding a Distribution List
Tip 315: Copy Sent Messages
Tip 316: Displaying Due by Dates
Tip 317: File, Save Attachment Location
Tip 318: Display 7 Days in the Calendar
Tip 319: Using Macros
Tip 320: SBS2003 and Account Order
Tip 321: Finding Folder Paths
Tip 322: Imported Appoint. are 'Busy'
Tip 323: You've Got Mail Sound
Tip 324: Can't Save Appointments
Tip 325: Who is Requesting Receipts?
Tip 326: Change the Contacts Tab Order
Tip 327: More on Changing Tab Order
Tip 328: Holidays in Outlook 2002
Tip 329: Exposing MAPI Fields
Tip 330: Delete Recurring Appoint.
Tip 331: Date Shortcuts
Tip 332: Using the Date Picker
Tip 333: Prevent Accidental Sending
Tip 334: More: Accidental Sending
Tip 335: Select Weeks
Tip 336: Send Messages Later
Tip 337: Appointment Reminders
Tip 338: Editing Received Email
Tip 339: Store Sent Items in the Inbox
Tip 340: Remove Lost Password
Tip 341: Save Normal.dot?
Tip 342: Printing Messages
Tip 343: OutlookLive Service Unavail.
Tip 344: Finding Empty Folders
Tip 345: SmartTags
Tip 346: New Item Row
Tip 347: Indiana Time Zones and DST
Tip 348: Merging Calendars
Tip 349: Move, Copy or Import?
Tip 350: Missing Export Menu
Tip 351: Office 2003 and a Bad Update
Tip 352: Alternate Calendars
Tip 353: Read Only Attachments
Tip 354: Changing Quick Flag Colors
Tip 355: Calendar History
Tip 356: Resetting Views
Tip 357: Office 2007 Beta 2 Download
Tip 358: Outlook 2007 Known Issues
Tip 359: OL2007 Known Issues (corrt.)
Tip 360: Copy Text Into New Messages
Tip 361: Send Files From Explorer
Tip 362: Send To... Questions
Tip 363: See More Navigation Calendars
Tip 364: Go to Appointment Date
Tip 365: View All Day Events
Tip 366: Signatures on Custom Forms
Tip 367: Hide Form Fields
Tip 368: Jump in Message List
Tip 369: Emailing a Calendar
Tip 370: Apply Labels
Tip 371: Clear the Autocomplete Cache
Tip 372: Test Drive Office 2007 Beta
Tip 373: Filters and the From Field
Tip 374: Reply to All
Tip 375: OL 2007: Contact Linking
Tip 376: Calendar Printing Assistant

Do you have two dates listed on each calendar square, one on the left and one on the right? If so, it means you have an alternate calendar enabled. To disable it (or check it out), go to Tools, Options, Calendar Options and toggle the checkmark for Enable alternate calendar.