Entonces recibí este error: # 1066 - Tabla / alias no únicos: 'Compra'

Estoy tratando de hacer lo siguiente:

    SELECT Blank.BlankTypeCode
          ,Blank.BlankCode
          ,Payment.Amount
          ,Payment.Type
          ,Purchase.PurchaseDate
          ,Payment.DatePaid
FROM Blank
INNER JOIN Ticket
ON Blank.BlankCode = Ticket.Blank_BlankCode
INNER JOIN MCO_Blank
ON Blank.BlankCode = MCO_Blank.Blank_BlankCode
INNER JOIN Purchase
ON  Ticket.PurchaseID = Purchase.PurchaseID
INNER JOIN Purchase
ON MCO_Blank.PurchaseID = Purchase.PurchaseID
INNER JOIN Payment
ON Ticket.PurchaseID = Payment.PurchaseID
INNER JOIN Payment
ON MCO_Blank.PurchaseID = Payment.PurchaseID
WHERE Payment.Status = "Paid";

La tabla en blanco consiste en:

BlankCode,
IssueDate,
Status,
UserID, 
BlankTypeCode

La tabla de pago consta de:

Type,
Amount,
Status,
DueDate,
PurchaseID,
CurrencyRateDate

La tabla de compra consta de:

PurchaseID,
CustomerID,
PurchaseDate,
TotalFare,
TaxAmount,
CurrencyType,
Purchasecol

La mesa de entradas consta de:

Price,
PurchaseID,
Blank_BlankCode,
Blank_BlankTypeCode,
TicketType,
Airline_Name

La tabla MCO_Blank consta de:

Service,
Cost,
Description,
Purchase_PurchaseID,
Blank_BlankCode,
Blank_BlankTypeCode

No estoy seguro de cómo puedo hacer que esto funcione.