I have taken a look at this in an attempt to help John out, but haven't got much further, other than when I attempt a transaction for the first time, i get a transaction declined.
Any subsequent attempt gets the duplicate order message.
I have taken the source from the failed transaction page in each instance and a modified version is below
<order>
<merchantinfo>
<configfile>1000000000</configfile>
<keyfile>/path/1000000000.pem</keyfile>
<host>secure.linkpt.net</host>
<port>1129</port>
</merchantinfo>
<orderoptions>
<ordertype>SALE</ordertype>
<result>LIVE</result>
</orderoptions>
<payment>
<tax>2.4</tax>
<shipping>15.95</shipping>
<subtotal>29.95</subtotal>
<chargetotal>48.30</chargetotal>
</payment>
<billing>
<name>John</name>
<address1>S Garland St</address1>
<address2></address2>
<city>Lake</city>
<state>CO</state>
<zip>80226</zip>
<country>US</country>
<phone>303</phone>
<fax></fax>
<email>johntest@logo.com</email>
</billing>
<creditcard>
<cardnumber>4111111111111111</cardnumber>
<cardexpmonth>12</cardexpmonth>
<cardexpyear>12</cardexpyear>
<cvmvalue>123</cvmvalue></creditcard>
<shipping>
<name>John</name>
<address1>S Garland St</address1>
<address2></address2>
<city>Lake</city>
<state>CO</state>
<zip>80226</zip>
<country>US</country>
<items>1</items>
<weight>1</weight>
<total>29.95</total>
</shipping>
<transactiondetails>
<taxexempt>N</taxexempt>
<terminaltype>UNSPECIFIED</terminaltype>
<oid>bcdf1fd6f946e2bee1d24cee082cdb68</oid>
</transactiondetails>
<items>
<item>
<id>992</id>
<description>10 Budweiser Can Lights</description>
<price>29.95</price>
<quantity>1</quantity>
</item>
</items>
</order>
<r_csp></r_csp>
<r_time>Tue Oct 12 08:48:33 2010</r_time>
<r_ref></r_ref>
<r_error>SGS-000001: D:DeclinedXXUX:</r_error>
<r_ordernum>bcdf1fd6f946e2bee1d24cee082cdb68</r_ordernum>
<r_message>DECLINED</r_message>
<r_code></r_code>
<r_tdate>1286887713</r_tdate>
<r_score></r_score>
<r_authresponse>X07</r_authresponse>
<r_approved>DECLINED</r_approved>
<r_avs></r_avs>
Test 2
<order>
<merchantinfo>
<configfile>1000000000</configfile>
<keyfile>/path/1000000000.pem</keyfile>
<host>secure.linkpt.net</host>
<port>1129</port>
</merchantinfo>
<orderoptions>
<ordertype>SALE</ordertype>
<result>LIVE</result>
</orderoptions>
<payment>
<tax>2.4</tax>
<shipping>31.9</shipping>
<subtotal>29.95</subtotal>
<chargetotal>64.25</chargetotal>
</payment>
<billing>
<name>John</name>
<address1>S Garland St</address1>
<address2></address2>
<city>Lake</city>
<state>CO</state>
<zip>80226</zip>
<country>US</country>
<phone>3039193007</phone>
<fax></fax>
<email>johntest@logo.com</email>
</billing>
<creditcard><cardnumber>4111111111111111</cardnumber>
<cardexpmonth>12</cardexpmonth>
<cardexpyear>12</cardexpyear>
<cvmvalue>456</cvmvalue>
</creditcard>
<shipping>
<name>John</name>
<address1>S Garland St</address1>
<address2></address2>
<city>Lake</city>
<state>CO</state>
<zip>80226</zip>
country>US</country>
<items>1</items>
<weight>1</weight>
<total>29.95</total>
</shipping>
<transactiondetails>
<taxexempt>N</taxexempt>
<terminaltype>UNSPECIFIED</terminaltype>
<oid>bcdf1fd6f946e2bee1d24cee082cdb68</oid>
</transactiondetails>
<items>
<item>
<id>992</id>
<description>10 Budweiser Can Lights</description>
<price>29.95</price>
<quantity>1</quantity>
</item>
</items>
</order>
<r_csp></r_csp>
<r_time>Tue Oct 12 08:57:19 2010</r_time>
<r_ref></r_ref>
<r_error>SGS-005003: The order already exists in the database.</r_error>
<r_ordernum>bcdf1fd6f946e2bee1d24cee082cdb68</r_ordernum>
<r_message></r_message>
<r_code></r_code>
<r_tdate></r_tdate>
<r_score></r_score>
<r_authresponse></r_authresponse>
<r_approved>DUPLICATE</r_approved>
<r_avs></r_avs>
If anyone has used this payment gateway before, can I check, do the test c/c details work in a live environment ?