Erased Addresses On FDC

One thing that has not been addressed (sorry, I couldn't resist) here so far is different types of addressing. Some are typed, some are neatly written, and some are scrawled. Scrawling is definitely a value downgrade compared to typed or neatly written.

I literally see thousands of FDCs each month and I have seen some silly things - the one that stands out the most is fools who have used white-out to cover an address.

Multiple stamps on a FDC is far more common for foreign FDCs (since they tend to issue sets of stamps instead of a single stamp), but in addition to the combo FDCs someone else mentioned, there are multi-design US issues that are often found on a single FDC, but also it is not that uncommon to find plate blocks or plain blocks of 4, particularly on older FDCs (they were probably most 40s & 50s, but you will find them earlier and later)

I mentioned the combo FDCs. As for plate blocks on FDCs, my experience is limited mostly to US airmail and aviation themed topicals, and have found them to be present from the 1930s down to the present. I have a collection of US airmail material in two Lindner binders of singles, plate blocks and booklet panes, and FDCs. The earliest airmail plate block FDCs in my collection are C16 (1931) and C17 (1932). From C20 (1937) to C150 (2012) I have plate block FDCs for almost every issue (excluding booklet issues, where I have FDCs with booklet panes). I don't know if plate block FDCs were more common in the 1940s and 1950s, but I think there was more interest in plate blocks in the past than at present. But even with modern issues, in accumulating my collection of US airmail and topical aviation FDCs, I've found the modern covers with plate blocks to command a modest premium over FDCs with singles.

Basil